CN212104115U - Foundation pit supporting system - Google Patents

Abstract

The utility model discloses a foundation pit supporting system, which comprises a supporting wall formed by inner side piles and positioned at the edge of a foundation pit, and a composite pile positioned at one side of the supporting wall, which is far away from the foundation pit, wherein the composite pile comprises a jet grouting pile and a pipe pier positioned in the jet grouting pile; an anchor cable is arranged between the supporting wall and the composite pile, one end of the anchor cable is fixedly connected to the pipe pier, and the other end of the anchor cable penetrates through the supporting wall and then is connected to the purlin; the anchor cable extends downwards from the purlin along the inclined direction and is connected to the pipe pier. Set up in this application by the pipe mound and the pile that spouts soon forms composite pile, the pipe mound is used for fixed anchor rope, makes the anchor rope have a stable fixed point in the soil body, and on the external force that the pipe mound received transmitted the pile that spouts soon, the pile that spouts soon provides bigger counter-force for the pipe mound, avoids the pipe mound to produce the displacement under the pulling force of anchor rope, reduces the prestressing force of anchor rope to reduce the pulling force to enclosing the purlin, influence the security of foundation ditch.

Description

Foundation pit supporting system

Technical Field

The utility model relates to a foundation ditch supporting system.

Background

When the underground structure operation is carried out in the city, for the excavation region that reduces the foundation ditch, all need set up supporting system to reduce the influence to other buildings around the foundation ditch, nevertheless because building density is bigger and bigger in the city, traffic is crowded, and the place is narrow and small, and geological conditions selectivity is poor, and the neighbouring existing building of deep basal pit is very general, makes the deep basal pit support pattern selection receive the restriction. The supporting structure of the pile with the inner support and the supporting structure of the pile wall with the inner support can effectively control deformation, but excavation is inconvenient, the manufacturing cost is high, and the construction period is long. The supporting structure of pile plus anchor rod is convenient to dig, low in cost and convenient to construct, but the anchor rod is limited to be red line in many places, so that the supporting structure is not allowed to be used.

The ground horizontal anchor pile is a supporting structure type that an anchor pile is constructed in a soil body stable area at a certain distance from the outer side of a foundation pit, a pull rod is pulled above a groove or a natural terrace dug on the back of a supporting pile, one end of the pull rod is connected with a crown beam on the supporting pile, the other end of the pull rod is connected with the crown beam on the anchor pile, a certain prestress is applied to the pull rod through a connecting fastener, and a part of soil pressure of the soil body on the upper portion of the foundation pit acting on the supporting pile is transmitted to the anchor pile. Has the advantages of low cost, simple and convenient operation, flexible use, less occupied construction clearance and the like. However, the horizontal anchor pulling piles can only be arranged on a shallow foundation and only one layer, so that the horizontal pulling force provided by the anchor pulling piles is not large, and large deformation can be generated.

SUMMERY OF THE UTILITY MODEL

In order to solve the problems, the application firstly provides a foundation pit supporting system which comprises a supporting wall formed by inner side piles and positioned at the edge of a foundation pit and a composite pile positioned at one side of the supporting wall, which is far away from the foundation pit, wherein the composite pile comprises a jet grouting pile and a pipe pier positioned in the jet grouting pile, the pipe pier is a prefabricated hollow pipe pier, and the pipe pier is provided with a pipe pier hole which extends along the vertical direction and is used for a jet grouting pipe to pass through; an anchor cable is arranged between the supporting wall and the composite pile, one end of the anchor cable is fixedly connected to the pipe pier, and the other end of the anchor cable penetrates through the supporting wall and then is connected to the purlin; the anchor cable extends downwards from the purlin along the inclined direction and is connected to the pipe pier. And no connecting beam is arranged between the composite pile and the wall constructed by the SMW method.

In this excavation supporting system, composite pile has been set up specially, this composite pile is formed by pipe pier and jet grouting pile, pipe pier wherein is used for fixed anchor rope, make the anchor rope have a stable fixed point in the soil body, jet grouting pile is connected to back on the pipe pier, can make the external force that the pipe pier received transmit on the jet grouting pile, because jet grouting pile has bigger stability in the soil body, can provide bigger counter-force for the pipe pier, avoid the pipe pier to produce the displacement under the pulling force of anchor rope, reduce the prestressing force of anchor rope, thereby reduce the pulling force to enclosing the purlin, influence the security of foundation ditch.

Compared with the existing system for supporting the foundation pit by adopting the anchor rod, the construction method can be used for construction in a small range, particularly the construction of the jet grouting pile can be carried out at a position 5 meters away from the edge of the foundation pit, the occupied area of the construction is effectively reduced, and the influence on the existing buildings around the construction can be reduced.

Further, at least two pipe piers are arranged in the jet grouting pile at intervals in the vertical direction, and two adjacent pipe piers are connected together through a connecting part; each connecting part at least comprises two connecting rods which extend along the vertical direction and are arranged around the central axis of the jet grouting pile.

After being connected together by the connecting parts, the pipe piers form a whole, can sink once only and can transmit the stress of the pipe piers to resist external force. In the construction process, a construction method of sinking the pipe piers firstly and then constructing the jet grouting pile is adopted, and the space surrounded by all the connecting rods forms an insertion channel of a jet grouting pipe of the jet grouting pile machine for constructing the jet grouting pile, so that the jet grouting pile and each pipe pier form a whole.

Specifically, the connecting part is a cylindrical reinforcement cage extending along the vertical direction, and a main reinforcement of the reinforcement cage extending along the vertical direction is formed into a connecting rod; or the connecting rod is made of section steel. This setting can make the partial structure of composite pile be similar to the structure of bored concrete pile, makes composite pile can bear bigger external force, can also avoid the pipe mound to break away from the jet grouting pile, causes the inefficacy of anchor rope stretch-draw to influence the safety of foundation ditch.

In the height direction, at least one pipe pier is positioned below the set depth of the bottom surface of the foundation pit.

Because the pipe pier in this application is sunk to the underground, and on the anchor rope was connected to the pipe pier by enclosing purlin downwardly extending, the pipe pier can improve stable pull down for enclosing the purlin, especially when the pipe pier is located the setting for degree of depth below of the bottom surface of foundation ditch, because the soil body below the setting for degree of depth of the bottom surface of foundation ditch has higher stability, more can provide stable pulling force, provides bigger decurrent pulling force for the anchor rope simultaneously to the resistance to plucking ability of the inboard stake of reinforcing.

Specifically, the angle between the anchor line and the horizontal plane is 15-70 °. During specific construction, the selection can be carried out according to the depth of the foundation pit, so that the pipe pier can provide larger downward pulling force.

Secondly, the application also provides a construction method of the foundation pit supporting system, which is used for the construction of the foundation pit supporting system in the technical schemes, and comprises the following steps:

(1) two ends of the anchor cable are respectively called a pier end and a purlin enclosing end;

constructing the inner side piles to form a support wall, synchronously arranging the purlin enclosing ends of the anchor cables to the underground along with the construction of the inner side piles, and enabling the purlin enclosing ends of the anchor cables to penetrate through the support wall and then be positioned on one side of the support wall facing the inner direction of the foundation pit;

fixing the pipe pier end of the anchor cable on the pipe pier, sinking the pipe pier connected with the anchor cable to a set underground depth by using a steel sleeve, removing the steel sleeve after sinking the pipe pier, and constructing a jet grouting pile, wherein the pipe pier and the jet grouting pile form a composite pile;

when only one pipe pier is arranged, the lower end surface of the steel sleeve is pressed against the pipe pier when the pipe pier is sunk;

when at least two pipe piers are arranged, the steel sleeve is utilized to sink each pipe pier in sequence when the pipe piers are sunk, or the at least two pipe piers are connected in sequence to form a pipe pier part, and the steel sleeve is utilized to sink the pipe pier part; when the pipe pier part is sunk, the steel sleeve is sleeved on the pipe pier part, and the lower end surface of the steel sleeve is pressed against the pipe pier at the lowest end of the pipe pier part; the sinking of the inner side piles and the composite piles is not in sequence;

(2) the enclosing purlin connected with the anchor cable is called an anchor cable enclosing purlin;

when only one anchor cable enclosing purlin is arranged, the step (2) comprises the following steps:

(2.11) excavating a foundation pit, when the construction elevation of the anchor cable enclosing purlin is reached, pausing the excavation of the foundation pit, then constructing the anchor cable enclosing purlin, tensioning the anchor cable, and fixing the tensioned anchor cable on the anchor cable enclosing purlin;

(2.12) continuing excavation of the foundation pit until excavation of the foundation pit is completed;

when at least two anchor cable enclosing purlins are arranged, the step (2) comprises the following steps:

(2.21) excavating a foundation pit, pausing excavation of the foundation pit when the construction elevation of the first anchor cable enclosing purlin is reached, then constructing the first anchor cable enclosing purlin, tensioning the anchor cables corresponding to the first anchor cable enclosing purlin and fixing the anchor cables to the first anchor cable enclosing purlin;

(2.22) continuously excavating the foundation pit, when the construction elevation of the second anchor cable enclosing purlin is reached, suspending excavation of the foundation pit, constructing the second anchor cable enclosing purlin, tensioning the anchor cable corresponding to the second anchor cable enclosing purlin and fixing the anchor cable to the second anchor cable enclosing purlin;

(2.23) repeating the step (2.22) until the construction of all the anchor cable purlins and the tensioning and fixing of the corresponding anchor cables are completed;

and (2.24) continuing excavation of the foundation pit until the excavation of the foundation pit is finished.

In the construction method, the pipe pier is sunk firstly, and then the construction of the jet grouting pile is carried out, so that the pile hole formed when the pipe pier sinks can be effectively eliminated, the pipe pier can be effectively connected to the jet grouting pile in the formed composite pile, the displacement generated by pulling the anchor rope is avoided, and the anchor rope can generate stable prestress.

Before sinking the pipe pier, stirring soil by using a stirring pile machine to form loose soil, sinking the pipe pier into the loose soil by using a steel sleeve, and constructing a jet grouting pile after removing the steel sleeve;

or before sinking the pipe pier, using a rotary jet pile machine to carry out guniting treatment underground to form a cement-soil pile, before the cement-soil is initially set, sinking the pipe pier into the cement-soil pile by using a steel sleeve, removing the steel sleeve, and then using the rotary jet pile machine to carry out supplementary guniting on the cement-soil pile to complete the construction of the rotary jet pile.

When the pipe pier sinking device is constructed in a region with hard soil, the pipe pier sinking can not be smoothly completed, and the pipe pier sinking can be smoothly completed after soil is firstly stirred loose or a cement soil pile is firstly formed. When the construction of carrying out the jet grouting pile, because the soil body has been stirred the pine or form cement soil, can make the construction of jet grouting pile accelerate, can not cause the influence to the construction progress because of the construction of going on in advance stirring the pine with soil or forming cement soil pile, owing to accelerated sinking of pipe pier on the contrary, and more be favorable to the acceleration of construction progress.

Further, the inner side pile is a precast pile, a construction pile or a cast-in-place pile; the precast pile is preferably various pile bodies such as a steel sheet pile, H-shaped steel, a tubular pile and the like;

when the inner side pile is a precast pile, a first pile body hole in a through hole shape is formed in the pile body of the inner side pile, an anchor rope is freely arranged in the first pile body hole in a penetrating mode before the inner side pile is constructed, then the inner side pile is sunk underground, and the end, which surrounds a purlin, of the anchor rope penetrates through the supporting wall and is located on one side, facing the inner direction of the foundation pit, of the supporting wall; under the pulling of external force, the anchor cable can move relative to the inner side pile;

when the inner pile is a construction method pile, a second pile body hole in a through hole shape is arranged on the reinforcing section steel used as a stress reinforcing material, and an anchor cable is freely inserted in the second pile body hole; when the inner pile is constructed, after the pouring of the mixing pile is finished, the reinforcing section steel is inserted into the mixing pile to form a construction method pile; after the surrounding purlin end of the anchor cable penetrates through the supporting wall, the surrounding purlin end is positioned on one side of the supporting wall facing the inner direction of the foundation pit, and the anchor cable can move relative to the inner side pile under the pulling of external force;

when the inner side pile is a cast-in-place pile, the anti-condensation pipe is installed on the steel reinforcement cage, the anchor cable freely penetrates through the anti-condensation pipe, after the cast-in-place pile is poured, the surrounding purlin end of the anchor cable penetrates through the supporting wall and is located on one side of the supporting wall, facing the inner direction of the foundation pit, and the anchor cable can move relative to the inner side pile under the pulling of external force. In order to prevent cement soil from entering the anti-condensation pipe, when the anti-condensation pipe is made of hard pipelines such as a steel pipe and a hard plastic pipe, before the steel reinforcement cage is sunk, foam plastic or rubber blocks can be filled in the anti-condensation pipe; when the anti-condensation pipe is made of a hose such as a plastic pipe, the two ends of the anti-condensation pipe can be tied by elastic strips such as rubber strips.

According to different soil conditions, different pile types can be selected as the inner side piles.

Further, when the inner pile is a construction method pile, the anchor cable is sleeved with an outer sleeve which is fixed on the reinforcing section steel, two ends of the outer sleeve both exceed the outer wall of the mixing pile outwards, and an inner cavity of the outer sleeve is formed into a second pile body hole;

when the inner side pile is a cast-in-place pile, both ends of the anti-condensation pipe outwards exceed the outer wall of the cast-in-place pile.

In order to prevent cement soil from entering the outer sleeve, when the outer sleeve is made of hard pipelines such as a steel pipe and a hard plastic pipe, foam plastic or rubber blocks can be filled in the outer sleeve before the outer sleeve is sunk underground; when the outer sleeve is made of a hose such as a plastic pipe, the two ends of the outer sleeve can be tied by using a rubber strip or a rope, but the anchor cable can be stretched.

Before tensioning the anchor cable, firstly, a tensioning groove is formed in a path through which the anchor cable passes, so that the anchor cable is arranged in the tensioning groove.

When carrying out the stretch-draw to the anchor rope, the anchor rope need be cut the soil body, just can reach the settlement position to the tensioning can hinder the anchor rope to the cutting of soil body, still can cause the destruction to the anchor rope sometimes in the harder region of partial soil property, perhaps when having great debris in the soil body. After the tensioning groove is formed, the anchor cable can smoothly reach a set position through the tensioning groove, and the situation is avoided.

Specifically, in order to enable the rotary jet grouting pile to better wrap the pipe pier, the guniting pipe of the rotary jet grouting pile machine penetrates through the inner cavity of the pipe pier when the rotary jet grouting pile is constructed. The design can enable the rotary spraying pile to completely wrap the pipe pier, so that the pipe pier is stably kept in the rotary spraying pile.

Drawings

Figure 1 is a schematic structural view of a first embodiment of an excavation supporting system.

Fig. 2 is a schematic structural view of the first pipe pier.

Figure 3 is a schematic illustration of the first retaining wall after completion of construction of the first embodiment of the foundation pit support system.

Figure 4 is a schematic illustration of the first pipe pier after it has been lowered during the construction of the first embodiment of the foundation pit support system.

Figure 5 is a schematic illustration of a first jet grouting pile after completion of construction of the first embodiment of the foundation pit support system.

Fig. 6 is a schematic diagram of the first anchor cable purlin after the first anchor cable purlin is constructed in the first embodiment of the foundation pit supporting system.

Figure 7 is a schematic illustration of the first cable bolt being tensioned during construction of the first embodiment of the foundation support system.

Figure 8 is a schematic illustration of the excavation of a first excavation being completed during the construction of the first embodiment of the excavation supporting system.

Figure 9 is a schematic structural view of a second embodiment of the excavation supporting system.

Fig. 10 is a schematic structural view of a pier portion.

Fig. 11 is an enlarged view of a portion H in fig. 10.

Fig. 12 is a view from E-E in fig. 10.

Figure 13 is a schematic illustration of the second retaining wall after completion of construction of the second embodiment of the excavation supporting system.

Figure 14 is a schematic illustration of a mixing pile machine being used to mix loose the subsurface earth during the construction of the second embodiment of the foundation pit support system.

Figure 15 is a schematic illustration of the completed pipe pier portion after it has been lowered during construction of the second embodiment of the foundation pit support system.

Figure 16 is a schematic illustration of a second embodiment of the excavation supporting system after completion of the second jet grouting pile.

Fig. 17 is a schematic diagram of the second anchor cable purlin a after construction of the second embodiment of the foundation pit supporting system.

Fig. 18 is a schematic view of the second anchor cable purlin B after construction, in the second embodiment of the foundation pit support system.

Figure 19 is a schematic illustration of the second embodiment of the excavation supporting system after the second excavation has been completed.

FIG. 20 is a schematic view showing the outer tube fixed to the reinforcing steel.

Detailed Description

Example 1

Referring to fig. 1, a first foundation pit support system includes a first retaining wall 40 at an edge of a first foundation pit 200 and a first composite pile 50 at a side of the first retaining wall 40 facing away from the first foundation pit, the first composite pile 50 including a first jet grouting pile 52 and a first pipe pier 51 located within the first jet grouting pile 52. In this embodiment, the first support wall 40 is a steel sheet pile wall formed by interlocking U-shaped steel sheet piles. The first pipe block 51 is located below the set depth of the first bottom surface 201 of the first foundation pit 200 in the height direction. The U-shaped steel sheet pile forming the steel sheet pile wall is the inner side pile. Reference numeral 110 denotes a ground surface in the present embodiment.

Referring to fig. 2, the first pipe block 51 is a prefabricated hollow pipe block, and has a first pipe block hole 514 extending in a vertical direction for allowing a guniting pipe to pass through. In this embodiment, the first pipe pier 51 specifically includes a first pipe pier body 511 made of a steel pipe, and two first anchor cable holes 5113 are formed in the side wall of the first pipe pier body 511. The outer peripheral surface of the upper portion of the first pipe pier body 511 is constricted radially inward to form a first throat 512, and a first stepped portion 513 is formed between the first throat 512 and the first pipe pier body 511. In this embodiment, the first necking portion 512 is a section of steel pipe sleeved inside the first pipe pier body 511, and the first necking portion is welded on the first pipe pier body. An end surface of the first pipe pier body 511 facing the first throat portion is formed as a first stepped portion. The guniting pipe is the guniting pipe of the rotary jet pile machine when the rotary jet pile is constructed.

A first anchor rope 61 is arranged between the first retaining wall 40 and the first composite pile, one end of the first anchor rope 61 is fixedly connected to the first pipe pier, and the other end of the first anchor rope passes through the retaining wall and then is connected to the first purlin 41. With continued reference to fig. 2, in this embodiment, one end of first anchor line 61 is sequentially inserted through two first anchor line holes 5113 and then fixed to first anchor line 61 itself by anchor 618, so that first anchor line 61 is connected to first pipe pier 51.

First anchor line 61 extends downward in an oblique direction from first purlin 41 and is connected to first pipe pier 51. And there is no tie beam between the first composite pile and the first retaining wall. The first anchor cable 61 is made of steel stranded wire.

Angle β 1 between first anchor line 61 and the horizontal plane is 60 °. It is understood that in other embodiments, the angle β 1 may also be 15 °, 20 °, 40 ° or 70 °, with the angle β 1 being as large as possible.

The construction method of the first foundation pit supporting system comprises the following steps:

(1) referring to fig. 3, a first retaining wall 40 is constructed by sequentially sinking U-shaped steel sheet piles into the ground and engaging the U-shaped steel sheet piles with each other to form a steel sheet pile wall, which is the first retaining wall 40.

For ease of description, the two ends of first anchor line 61 are referred to as first purlin end 612 and first pipe pier end 613, respectively. Before sinking the U-shaped steel sheet pile, first the first anchor cable is inserted into the first pile hole on the pile body of the steel sheet pile, and after sinking the steel sheet pile, the first enclosing purlin end 612 of the first anchor cable is located on one side of the first retaining wall 40 facing the inside direction of the foundation pit. Namely, the surrounding purlin end of the anchor cable penetrates through the supporting wall and is positioned on one side of the supporting wall facing the inner direction of the foundation pit.

The first pier end 613 of the first anchor line is fixed to the first pier 51.

Referring to fig. 4 and 5, the first pipe pier 51 is lowered to a set depth in the ground using a first steel casing 55. After completion of the sinking of the first pipe pier 51, the first steel casing 55 is removed, and then the first jet grouting pile 52 is constructed, the first pipe pier 51 and the first jet grouting pile 52 forming the first composite pile 50.

When sinking the first pipe pier, the lower terminal surface of first steel casing pipe 55 supports and leans on first step portion 513, avoids first pipe pier to sink the in-process, breaks away from first steel casing pipe or takes place the slope, influences the normal sinking of first pipe pier.

When the first jet grouting pile is constructed, the jet grouting pipe of the jet grouting pile machine is inserted into the first pipe pier hole 514 of the first pipe pier 51, so that the first jet grouting pile completely wraps the first pipe pier.

In this embodiment, the construction of the supporting wall is completed first, and then the composite pile is constructed, and it can be understood that in other embodiments, the composite pile may be constructed first, and then the supporting wall may be constructed, or the construction of the supporting wall and the composite pile may be performed simultaneously.

(2) The first purlin 41 to which the first anchor line is connected is referred to as a first anchor line purlin.

In this embodiment, only one anchor cable purlin is provided, and the step (2) is specifically performed according to the following sub-steps:

(2.11) referring to fig. 6 and 7, excavating the first foundation pit 200, when the construction elevation of the first anchor cable enclosing purlin is reached, suspending the excavation of the first foundation pit 200, constructing the first anchor cable enclosing purlin, tensioning the first anchor cable 61, and fixing the tensioned first anchor cable 61 on the first anchor cable enclosing purlin. Before the first anchor cable is tensioned, a first tensioning slot 220 is firstly formed in a path through which the first anchor cable passes, so that the first anchor cable is arranged in the first tensioning slot 220. In this embodiment, the first anchor cable surrounding purlin is composed of two rows of i-beams, the two rows of i-beams extend along the horizontal direction and are arranged side by side at intervals along the vertical direction, and the first surrounding purlin end 612 of the first anchor cable 61 penetrates through a gap between the two rows of section steels in the vertical direction and is fixed on the first anchor cable surrounding purlin. The structure of first anchor rope purlin of enclosing in this embodiment also is called double pin I-steel construction.

(2.12) referring to fig. 8, the excavation of the first foundation pit is continued until the excavation of the first foundation pit is completed.

In this embodiment, after the sinking of the first pipe pier is completed, the hole wall of the hole formed by the sinking of the first pipe pier collapses after the first steel casing pipe is removed, and the construction of the first jet grouting pile is directly performed. It will be appreciated that in other embodiments, during construction of a more stable earthen region, after completion of the sinking of the first pipe pier and after removal of the first steel casing, the hole formed by the sinking of the first pipe pier remains intact and requires filling of the hole with earth whose top surface of the earth is no more than 1/3 degrees from the ground. If the hole wall of the hole collapses, but the collapsed earthwork is less, the hole still needs to be filled with soil, and after the filling is completed, the distance from the top surface of the earthwork in the hole to the ground is not more than 1/3 of the depth of the hole.

Example 2

Referring to fig. 9, the second foundation pit supporting system includes a second retaining wall 10 at an edge of the second foundation pit 400 and a second composite pile 20 at a side of the second retaining wall 10 facing away from the second foundation pit, the second composite pile 20 includes a second jet grouting pile 22 and three second pipe piers arranged in the second jet grouting pile 22 at intervals in the vertical direction, and referring to fig. 10, for convenience of description, the three second pipe piers are respectively referred to as a second pipe pier a211, a second pipe pier B212 and a second pipe pier C213 from top to bottom. The second pipe pier a211 and the second pipe pier B212 are connected together by a first connection 216, and the second pipe pier B212 and the second pipe pier C213 are connected together by a second connection 217. The three second pipe blocks are formed as one pipe block portion 21 together with the first connecting portion and the second connecting portion. Reference numeral 120 denotes a ground surface in the present embodiment.

In the height direction, the second pipe pier B212 and the second pipe pier C2132 are located below the set depth of the second bottom surface 401 of the second foundation pit 400.

In this embodiment, referring to fig. 20, the second supporting wall 10 is an SMW-process wall, and is specifically formed by mixing piles 101 overlapping each other in the radial direction and H-steel piles 102 inserted into the mixing piles 101 at intervals.

The three second pipe piers are prefabricated hollow pipe piers, please refer to fig. 10, fig. 11 and fig. 12, wherein the second pipe pier C213 has a second pipe pier hole 2135 extending in the vertical direction and used for the guniting pipe to pass through. In this embodiment, the second pipe pier C213 specifically includes a second pipe pier body 2131 made of a steel pipe, and two second anchor cable holes 2134 are formed in a side wall of the second pipe pier body 2131. The outer peripheral surface of the upper portion of the second pipe pier body 2131 is radially inwardly shrunk to form a second choke portion 2132, and a second step portion 2133 is formed between the second choke portion 2132 and the second pipe pier body 2131. In this embodiment, the second choke 2132 is a section of steel pipe sleeved in the second pipe pier body 2131, and the second choke is welded to the first pipe pier body. An end surface of the second pipe pier body 2131 facing the second throat portion is formed as a second stepped portion. The guniting pipe is the guniting pipe of the rotary jet pile machine when the rotary jet pile is constructed.

The second pipe pier a211 and the second pipe pier B212 are similar to the second pipe pier C213 in structure, and are different only in that no second choke is provided, and the outer diameters of the second pipe pier a211 and the second pipe pier B212 are the same as the outer diameter of the second choke 2132, that is, the outer diameters of the second pipe pier a211 and the second pipe pier B212 are smaller than the outer diameter of the second pipe pier body 2131, so that a second steel sleeve 25, which will be described later, can be pressed against the second stepped portion 2133 after passing through the second pipe pier a211 and the second pipe pier B212.

In this embodiment, the first connection portion 216 is formed by six first connection rods 2161, the six first connection rods 2161 are angle steels, the six first connection rods 2161 are uniformly spaced, and two ends of each first connection rod are respectively connected to the opposite end surfaces of the second pipe pier a211 and the second pipe pier B212.

The second connecting portion 217 is constituted by six second connecting rods 2171, the six second connecting rods 2171 are each an angle steel, the six second connecting rods 2171 are arranged at regular intervals, and one end of each second connecting rod is connected to the downward-facing end surface of the second pipe pier a211, and the other end of the second connecting rod 2171 is connected to the upward-facing end surface of the second throat portion 2132 of the second pipe pier C213. The six first connecting rods 2161 and the six second connecting rods 2171 are all arranged around the central axis of the second jet grouting pile, so that the space surrounded by the first connecting rods and the second connecting rods is formed as an insertion channel of a jet grouting pipe of the jet grouting pile machine for constructing the jet grouting pile.

A second anchor cable is arranged between the second retaining wall 10 and the second composite pile 20, one end of the second anchor cable is fixedly connected to the second pipe pier, and the other end of the second anchor cable penetrates through the second retaining wall and then is connected to the second purlin.

In this embodiment, three second anchor cables and two second purlins are provided, and the three second anchor cables are connected to three second pipe piers respectively. For convenience of description, the second anchor line connected to the second pipe pier a211 is referred to as a second anchor line a31, the second anchor line connected to the second pipe pier B212 is referred to as a second anchor line B32, and the second anchor line connected to the second pipe pier C213 is referred to as a second anchor line C33. The two second purlins are respectively called a second purlin a111 and a second purlin B112 from top to bottom. The structure of the two second purlins in this embodiment is the same as the structure of the first purlin in embodiment 1, and is not described again.

A second anchor line a31 and a second anchor line B32 are both connected to a second purlin a111, and a second anchor line C33 is connected to a second purlin B112.

The connection mode of each second anchor rope and second pipe pier is with the connection mode of first anchor rope and first pipe pier, and the connection mode of purlin is enclosed with first anchor rope and the first connection mode of enclosing to each second anchor rope and second, no longer gives unnecessary details.

And no connecting beam is arranged between the second composite pile and the second supporting wall.

Each second anchor line extends downwards along the inclined direction from the connected second purlin and is connected to the corresponding second pipe pier, wherein the included angle alpha 1 between the second anchor line A31 and the horizontal plane is 20 degrees, the included angle alpha 2 between the second anchor line B32 and the horizontal plane is 60 degrees, and the included angle alpha 3 between the second anchor line C33 and the horizontal plane is 70 degrees. Of course, the included angle between each second anchor cable and the horizontal plane can be selected between 15 degrees and 70 degrees according to specific requirements. In order to fully utilize the second composite piles, the included angle between each second anchor cable and the horizontal plane is preferably gradually increased from top to bottom.

In this embodiment, connecting portion between two adjacent second pipe piers adopt the angle steel setting, can understand, in other embodiments, can also adopt round steel, channel-section steel or billet to make. Or the connecting part is made of a steel reinforcement cage, and the main reinforcement of the steel reinforcement cage becomes a connecting rod for connecting the two second pipe piers.

The construction method of the second foundation pit supporting system comprises the following steps:

(1) referring to fig. 13, a second supporting wall 10 is constructed, and the second supporting wall 10 is a wall made by SMW process. Referring to fig. 20, the mixing piles 101 are constructed, the mixing piles 101 are overlapped with each other in the radial direction, and then H-shaped steel piles 102 are inserted into the mixing piles 101 at intervals to form the SMW-process wall. The H-shaped steel pile 12 is reinforced section steel.

Referring to fig. 20, in order to avoid that the second anchor cable is bonded by the cement soil in the mixing pile 101, which makes it difficult to stretch the second anchor cable, an outer sleeve 103 is welded to the H-shaped steel pile 102, the outer sleeve is made of steel pipe, two ends of the outer sleeve respectively penetrate two flanges of the H-shaped steel pile, and the second anchor cable is inserted into the outer sleeve, so as to reduce the contact between the second anchor cable and the cement soil. To avoid contact of the second anchor cable with the soil cement to the maximum extent, in this embodiment, both ends of the outer casing pipe extend outward beyond the outer wall of the mixing pile 101, as viewed in the vertical direction. In order to reduce the damage to the second anchor cable, the two ends of the outer sleeve are rounded, the outer sleeve is inclined downwards, and the inclination angle of the outer sleeve is approximately the same as that of the second anchor cable sleeved in the outer sleeve. The inner cavity of the outer sleeve is formed into a second pile body hole.

Before the H-shaped steel pile 102 sinks, after the second anchor cable penetrates through the outer sleeve, foam plastics are filled in the outer sleeve, and the amount of cement soil entering the outer sleeve in the H-shaped steel pile sinking process is reduced. It can be understood that in other embodiments, a plastic pipe can be used as the outer sleeve, when the plastic pipe is used as the outer sleeve, the two ends of the outer sleeve are fastened by a rubber strip or a rope, the outer sleeve is bound on the H-shaped steel pile, the outer sleeve is prevented from being separated from the H-shaped steel pile, and cement soil is prevented from entering the outer sleeve.

And two ends of each second anchor cable are respectively called a second pipe pier end and a second purlin end, and the second pipe pier end of each second anchor cable is fixed on the corresponding second pipe pier.

In this example, the soil in the construction area is hard, it is difficult to directly sink the pipe pier 21 underground, and in order to smoothly sink the pipe pier 21 underground, please refer to fig. 14, a mixing pile machine is used to mix the soil to form loose soil 26.

Referring to fig. 15, the pipe pier portion 21 is sunk into the loose soil 26 by the second steel sleeve 25 to reach a set depth, when the pipe pier portion 21 is sunk, the second steel sleeve 25 is sleeved on the pipe pier portion 21, and the lower end surface of the second steel sleeve 25 abuts against the second step portion 2133 of the second pipe pier C213, so that the pipe pier portion 21 is prevented from being separated from the first steel sleeve or inclined in the sinking process, and the pipe pier portion 21 is prevented from being bent when abutting against the top or middle portion of the pipe pier portion 21, which affects the normal sinking of the pipe pier portion. The second steel casing 25 is removed.

Referring to fig. 16, a second jet grouting pile 21 is constructed, and when the second jet grouting pile is constructed, a jet grouting pipe of a jet grouting pile machine sequentially passes through each second pipe pier. Each second pipe pier and second jet-grouting pile form a second composite pile 20.

(2) The second enclosing purlin a111 connected with the second anchor line a31 and the second anchor line B32 is called a second anchor line enclosing purlin a, and the second enclosing purlin B112 connected with the second anchor line C33 is called a second anchor line enclosing purlin B.

This embodiment is provided with two anchor rope purlins, and this step (2) specifically carries out according to the substep as follows:

(2.21) referring to fig. 17, a second foundation pit 400 is excavated, when the construction elevation of the second anchor rope enclosing purlin a is reached, the excavation of the second foundation pit 400 is suspended, then the second anchor rope enclosing purlin a is constructed, the second anchor rope a31 and the second anchor rope B32 are tensioned, and the tensioned second anchor rope a31 and second anchor rope B32 are fixed to the second anchor rope enclosing purlin a.

(2.22) referring to fig. 18, continuing to excavate the second foundation pit, suspending excavation of the second foundation pit when the construction elevation of the second anchor cable surrounding purlin B112 is reached, then constructing the second anchor cable surrounding purlin B, tensioning the second anchor cable C33, and fixing the tensioned second anchor cable C33 to the second anchor cable surrounding purlin B.

(2.24) referring to fig. 19, the excavation of the second foundation pit is continued until the excavation of the second foundation pit is completed.

In this embodiment, only two second anchor cable purlins are provided, and it can be understood that in other embodiments, when three or more second anchor cable purlins are provided, the method further includes a substep (2.23), where the substep (2.23) is repeated substep (2.22), until all the second anchor cable purlin construction and corresponding second anchor cable tensioning and fixing are completed.

Before the second anchor cable is tensioned, a second tensioning groove 320 is firstly formed in a path through which the second anchor cable passes, so that the second anchor cable is arranged in the second tensioning groove 320.

In this embodiment, when sinking the pipe pier portion, the soil body is stirred loose by the pile stirring machine to form loose soil. It is understood that in other embodiments, in order to smoothly sink the pipe pier portion to the ground, before sinking the pipe pier, a jet grouting process is first performed in the ground by using a jet grouting machine to form a cement pile, before the cement pile is initially set, the pipe pier portion is sunk into the cement pile by using a steel sleeve, and after removing the steel sleeve, a supplementary jet grouting process is performed on the cement pile by using the jet grouting machine to complete the construction of the jet grouting pile.

Of course, if the construction area is a soft soil layer, the pipe pier can be directly sunk to the ground.

It will be appreciated that in other embodiments, cast-in-place piles may also be employed as the inboard piles. When the filling pile is used as the inner pile,

install on the steel reinforcement cage and prevent the condensation pipe, wear to establish in this prevents the condensation pipe with the anchor rope freely, then pack foamed plastic in preventing the condensation pipe intussuseption, or plug up the mouth of pipe of preventing the condensation pipe with cement, but do not influence the stretch-draw to the anchor rope, prevent that the condensation pipe can steel pipe or plastic tubing. After pouring of the cast-in-place pile is completed, the purlin enclosing end of the anchor cable penetrates through the supporting wall and is located on one side, facing the inner direction of the foundation pit, of the supporting wall, and the anchor cable can move relative to the inner side pile under the pulling of external force. In order to avoid great inconvenience caused by tensioning of the anchor cable by concrete, two ends of the anti-condensation pipe both exceed the outer wall of the cast-in-place pile outwards.

Claims (5)

1. The foundation pit supporting system is characterized by comprising a supporting wall formed by inner side piles and positioned at the edge of a foundation pit and a composite pile positioned on one side, away from the foundation pit, of the supporting wall, wherein the composite pile comprises a jet grouting pile and a pipe pier positioned in the jet grouting pile, the pipe pier is a prefabricated hollow pipe pier, and the pipe pier is provided with a pipe pier hole which extends in the vertical direction and is used for a guniting pipe to pass through; an anchor cable is arranged between the supporting wall and the composite pile, one end of the anchor cable is fixedly connected to the pipe pier, and the other end of the anchor cable penetrates through the supporting wall and then is connected to the purlin; the anchor cable extends downwards from the purlin along the inclined direction and is connected to the pipe pier.

2. The foundation pit supporting system according to claim 1, wherein the system comprises at least two pipe piers which are arranged in the jet grouting pile at intervals in the vertical direction, and two adjacent pipe piers are connected together through a connecting part; each connecting part at least comprises two connecting rods which extend along the vertical direction and are arranged around the central axis of the jet grouting pile.

3. The excavation support system of claim 2,

the connecting part is a cylindrical reinforcement cage which extends along the vertical direction, and a main reinforcement of the reinforcement cage which extends along the vertical direction is formed into a connecting rod;

or the connecting rod is made of section steel.

4. The excavation support system of claim 1,

in the height direction, at least one pipe pier is positioned below the set depth of the bottom surface of the foundation pit.

5. The excavation support system of claim 1,

the angle between the anchor cable and the horizontal plane is 15-70 degrees.

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