阅读说明：本技术 一种后排桩锚的门架式双排桩体系及其施工方法 (Portal frame type double-row pile system of rear row pile anchor and construction method thereof ) 是由 郑翔 龚迪快 成怡冲 吴才德 许冠 王洁栋 于 2021-01-22 设计创作，主要内容包括：本发明公开了一种后排桩锚的门架式双排桩体系及其施工方法,包括前排桩和后排桩,通过高压旋喷施工工艺施工锚索,锚索布设于后排桩中相邻的两个桩之间；采用高压旋喷桩加固前排桩和后排桩之间的土体；施工前排桩和后排桩,桩顶之间用刚架梁连接；开挖至坑底,施工主体结构。本发明利于提高门架式双排桩的抗倾覆稳定性,且降低工程成本。(The invention discloses a portal double-row pile system of rear row pile anchors and a construction method thereof, wherein the portal double-row pile system comprises a front row pile and a rear row pile, an anchor cable is constructed through a high-pressure jet grouting construction process, and the anchor cable is arranged between two adjacent piles in the rear row pile; reinforcing soil between the front row of piles and the rear row of piles by adopting high-pressure jet grouting piles; constructing a front row pile and a rear row pile, and connecting pile tops by using a rigid frame beam; and (5) excavating to the bottom of the pit and constructing a main structure. The invention is beneficial to improving the anti-overturning stability of the portal frame type double-row pile and reducing the engineering cost.)

1. The utility model provides a portal frame formula double row pile system of back row pile anchor, includes preceding row pile (2) and back row pile (3), its characterized in that: the utility model discloses a pile structure, including the pit body (1), preceding campshed (2) are laid in the inboard of the pit body (1) along the medial surface edge of the pit body (1), back campshed (3) are laid in soil layer (4) around the lateral surface of the pit body (1), preceding campshed (2) and back campshed (3) constitute by a plurality of equidistant pile (5) of arranging, it consolidates through high-pressure jet grouting pile to be located soil body (41) between preceding campshed (2) and back campshed (3), connect through rigid frame roof beam (6) between preceding campshed (2) and the back campshed (3), anchor rope (7) are laid between two adjacent piles (5) in back campshed (3).

2. The portal double row pile system of rear row pile anchors according to claim 1, wherein: the distance between two adjacent piles (5) in the front row of piles (2) is 1m, and the distance between two adjacent piles (5) in the rear row of piles (3) is 3 m.

3. The portal double row pile system of rear row pile anchors according to claim 1, wherein: the distance between the front row of piles (2) and the rear row of piles (3) is 3 m.

4. The portal double row pile system of rear row pile anchors according to claim 1, wherein: the pile diameter of the pile (5) is 0.75m, the pile length of the pile (5) is 20m, and the concrete strength grade of the pile body of the pile (5) is C25.

5. The portal double row pile system of rear row pile anchors according to claim 1, wherein: 2 1860-grade steel strands with the diameter of 15.24mm are arranged in the anchor cable (7).

6. The portal double row pile system of rear row pile anchors according to claim 1, wherein: the rigid frame beam (6) is composed of gird beams (61) and connecting beams (62) between the gird beams (61), the gird beams (61) and the connecting beams (62) are concrete members, and the concrete strength grades of the gird beams (61) and the connecting beams (62) are C25.

7. The portal double row pile system of rear row pile anchors according to claim 1, wherein: the piles (5) in the rear row of piles (3) are hollow piles, and the anchor cables (7) are arranged in the piles (5) in the rear row of piles (3).

8. The construction method of the portal frame type double-row pile system of the rear row pile anchor is characterized by comprising the following steps of: the method comprises the following steps: constructing pile bodies of the front row of piles and the rear row of piles; constructing an anchor cable by a high-pressure jet grouting construction process; reinforcing soil between the front row of piles and the rear row of piles by adopting high-pressure jet grouting piles; constructing a front row pile and a rear row pile, and connecting pile tops by using a rigid frame beam; and (5) excavating to the bottom of the pit and constructing a main structure.

9. The construction method of the gate frame type double-row pile system of the rear row pile anchor according to claim 8, characterized in that: the diameter of the anchoring body of the anchor rope (7) is 400mm, the cement mixing amount of cement for grouting of the anchor rope (7) is 26%, common 42.5-grade cement is adopted as the cement, and the water cement ratio is 0.8-1.0.

10. The construction method of the gate frame type double-row pile system of the rear row pile anchor according to claim 8, characterized in that: the high-pressure jet grouting pile is used for reinforcing a soil body by adopting 5 rows of front and back reinforcement, the diameter of the high-pressure jet grouting pile is 700mm, the pile spacing is 500mm, the occlusion size is 200mm, and the cement mixing amount of the high-pressure jet grouting pile is 20%.

Technical Field

The invention relates to the field of foundation pit support, in particular to a portal frame type double-row pile system of rear row pile anchors and a construction method thereof.

Background

With the acceleration of urban construction pace, land resources are increasingly tense and scarce, the surrounding environment of buildings becomes more and more complex, and the foundation pit supporting engineering faces increasingly severe tests. At present, in foundation pit engineering, commonly used support forms include pile anchor support and pile support. Under some special conditions, due to the protection of underground space and surrounding environment, the limit on the pile-anchor supporting structure is more and more strict at present, and anchor cables are limited in a construction red line in many places, so that more supporting modes can only adopt pile supporting. However, for underground excavation of large space, the pile support not only affects the earth excavation and the construction of the underground structure, but also has difficulty in large span. Compared with the traditional pile support system and pile anchor system, the portal double-row pile support form is applied to more and more projects due to the advantages that the construction speed is high, the support body cannot invade the site outside the ground infrared line to cause underground obstacle and the like. However, when the depth of the foundation pit is deeper, the anti-overturning stability coefficient of the gantry type double-row pile system is often difficult to meet the standard design requirement, and the application of the gantry type double-row pile system to the deeper foundation pit is limited to the greatest extent. However, under some special conditions, the disadvantages of encroaching on the surrounding underground space and influencing the construction progress are still unsolved. In this case, the anti-overturning stability can be improved only by increasing the length of the double-row pile. Although the pile length is increased, the design requirement of the anti-overturning stability coefficient of the double-row pile support can be met to a certain extent, the engineering cost is increased to a greater extent.

Disclosure of Invention

The invention aims to provide a portal type double-row pile system of a rear row pile anchor and a construction method thereof, which are beneficial to improving the anti-overturning stability and reducing the engineering cost.

The technical scheme adopted by the invention for solving the problems is as follows:

the utility model provides a portal frame formula double row pile system of back row pile anchor, includes preceding row pile and back row pile, the inboard of the hole body is laid along the inboard side edge of the hole body to preceding row pile, and back row pile is laid in the soil horizon around the lateral surface of the hole body, and preceding row pile and back row pile constitute by a plurality of equidistant piles of arranging, and the soil body that is located between preceding row pile and the back row pile is consolidated through high-pressure jet grouting pile, connects through rigid frame roof beam between preceding row pile and the back row pile, and the anchor rope is laid between two adjacent piles in the back row pile.

As a further improvement of the above technical solution, a distance between two adjacent piles in the front row of piles is 1m, and a distance between two adjacent piles in the rear row of piles is 3 m.

As a further improvement of the above technical solution, the distance between the front row of piles and the rear row of piles is 3 m.

As a further improvement of the above technical solution, the diameter of the pile is 0.75m, the length of the pile is 20m, and the concrete strength grade of the pile body of the pile is C25.

As a further improvement of the technical scheme, 2 1860-grade steel strands with the diameter of 15.24mm are arranged in the anchor cable.

As a further improvement of the technical scheme, the rigid frame beam consists of the girt beams and the connecting beams between the girt beams, the girt beams and the connecting beams are concrete members, the construction speed is favorably improved, and the concrete strength grades of the girt beams and the connecting beams are all C25.

As a further improvement of the technical scheme, the piles in the rear row of piles are hollow piles, and the anchor cables are arranged in the piles in the rear row of piles, so that the anti-overturning stability of the rear row of piles is improved.

A construction method of a portal double-row pile system of a rear row pile anchor comprises the following steps: constructing pile bodies of the front row of piles and the rear row of piles; constructing an anchor cable by a high-pressure jet grouting construction process; reinforcing soil between the front row of piles and the rear row of piles by adopting high-pressure jet grouting piles; constructing a front row pile and a rear row pile, and connecting pile tops by using a rigid frame beam; and (5) excavating to the bottom of the pit and constructing a main structure.

As a further improvement of the technical scheme, the diameter of the anchoring body of the anchor rope is 400mm, the cement mixing amount of the cement used for grouting the anchor rope is 26%, the cement is common 42.5-grade cement, and the water cement ratio is 0.8-1.0.

As a further improvement of the technical scheme, the high-pressure jet grouting pile is used for reinforcing the soil body by adopting 5 rows of front and back reinforcement, the diameter of the high-pressure jet grouting pile is 700mm, the pile spacing is 500mm, the occlusion size is 200mm, and the cement mixing amount of the high-pressure jet grouting pile is 20%.

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

the anchor cable with lower engineering cost is adopted to improve the anti-overturning stability of the portal double-row pile, so that the occupied space outside the range of the portal double-row pile is reduced, the mode of improving the anti-overturning stability of the portal double-row pile by increasing the length of the double-row pile with higher cost is avoided, and the engineering cost is favorably controlled. Meanwhile, the anchor cable can be a slurry bag anchor cable and the like, and the anchor cable can be subjected to later grouting and can be recycled, so that temporary emergency reinforcement of foundation pit support is facilitated, and the engineering cost is reduced.

Drawings

Fig. 1 is a structural sectional view of a portal type double-row pile system of a rear row pile anchor according to an embodiment.

Fig. 2 is a schematic structural diagram of a gantry type double-row pile system of a rear row pile anchor in a top view.

Fig. 3 is a simplified schematic diagram of calculation of the anti-overturning stability of the portal double-row pile system of the rear row pile anchor of the embodiment.

Fig. 4 is a schematic structural diagram of a top view of a portal double-row pile system of a rear row pile anchor according to the second embodiment.

The pit comprises a pit body 1, front row piles 2, rear row piles 3, a soil layer 4, a soil body 41, piles 5, rigid frame beams 6, surrounding beams 61, connecting beams 62, anchor cables 7 and a main structure 8.

Detailed Description

The present invention will be described in further detail below by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting the present invention.

The first embodiment.

Referring to fig. 1-3, the portal double-row pile system of the rear row pile anchor of the present embodiment includes a front row pile 2 and a rear row pile 3, the front row pile 2 is disposed on the inner side of a pit body 1 along the edge of the inner side of the pit body 1, the rear row pile 3 is disposed in a soil layer 4 around the outer side of the pit body 1, the front row pile 2 and the rear row pile 3 are both composed of a plurality of piles 5 arranged at equal intervals, a soil body 41 between the front row pile 2 and the rear row pile 3 is reinforced by a high-pressure jet grouting pile, the high-pressure jet grouting pile is used for reinforcing the soil body by front and rear reinforcing 5 rows, the diameter of the high-pressure jet grouting pile is 700mm, the pile interval is 500mm, the engagement size is 200mm, the cement content of the high-pressure jet grouting pile is 20%, the front row pile 2 and the rear row pile 3 are connected by a rigid frame beam 6, an anchor cable 7 is disposed between two adjacent piles 5 in the rear row pile 3, the front row pile 2 and the rear row pile 3 are 3, the distance between two adjacent piles 5 in the front row of piles 2 is 1m, the distance between two adjacent piles 5 in the rear row of piles 3 is 3m, the pile diameter of each pile 5 is 0.75m, the pile length of each pile 5 is 20m, the concrete strength grade of the pile body of each pile 5 is C25, the anchor cable 7 is constructed by adopting a high-pressure rotary spraying construction process, 2 1860-grade steel stranded wires with the diameter of 15.24mm are arranged in the anchor cable 7, the anchor diameter of the anchor cable 7 is 400mm, the cement mixing amount of cement for grouting the anchor cable 7 is 26%, the cement adopts common 42.5-grade cement, the water cement ratio is 0.8-1.0, the rigid frame beam 6 is composed of a girt beam 61 and a connecting beam 62 between the girt beams 61, the girt beam 61 and the connecting beam 62 are both concrete members, the girt beam 61 is 600mm high, 1000mm wide, the connecting beam 62 is 600mm wide, and the girt beam 61 and the connecting beam 62 are both C25.

In summary, the construction steps of the portal double-row pile system of the rear row pile anchor of the invention are as follows:

the method comprises the following steps: constructing a pile body of a front row pile on the inner side of the pit body, and constructing a pile body of a rear row pile on the periphery of the pit body;

step two: constructing an anchor cable between two adjacent piles in the rear row of piles through a high-pressure jet grouting construction process;

step three: adopting a high-pressure jet grouting pile to reinforce a soil body between the front row of piles and the rear row of piles;

step four: constructing a front row pile and a rear row pile, and connecting pile tops by using a rigid frame beam;

step five: and (5) excavating to the bottom of the pit, and constructing a main body structure in the pit body.

In this embodiment, a method for calculating the anti-overturning stability of the portal double-row pile system of the rear row pile anchor is shown in the following formula:

in the formula:

K_f-an anti-overturning safety factor;

M_a、M_pthe moment standard values (kN m/m) of the active soil pressure and the passive soil pressure around the edge of the front row of piles are respectively;

g is the sum (kN) of the dead weights of the double-row piles, the rigid frame beams and the soil among the piles;

a_Gthe horizontal distance (m) from the gravity center of the double-row piles, the rigid frame beams and the soil among the piles to the edge of the front row of piles;

f-mean resultant force of water buoyancy (kN/m) acting on the bottom surface of the support, F ═ gamma_w(h_wa+h_wp)·B/2(γ_wIs the gravity of water, h_wa、h_wpThe distances from the underground water level to the pile bottom of the double-row pile before and after the double-row pile;

T_s-vertical pullout resistance (kN/m) provided by the rear anchor cables;

s_y-horizontal distance (m) of rear row anchor line to front row pile edge.

Example two.

Referring to fig. 4, the basic structure of a portal double-row pile system of a rear row pile anchor and the construction method thereof according to this embodiment is substantially the same as that of the first embodiment, except that: the piles 5 in the rear row of piles 3 are hollow piles, and the anchor cables 7 are arranged in the piles 5 in the rear row of piles 3.

The above description of the present invention is intended to be illustrative. Various modifications, additions and substitutions for the specific embodiments described may be made by those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.