Spliced pile supporting system suitable for upper-soft lower-hard multi-element stratum and construction method

Abstract

The invention relates to a spliced pile supporting system suitable for a multi-element stratum with a soft upper part and a hard lower part and a construction method. An existing support pile under the upper-soft and lower-hard multi-element stratum is large in construction noise, difficult to construct, prone to deviating and breaking and high in engineering cost. The structure comprises a reinforced concrete pile located on an upper soft stratum and a steel pipe pile located on a lower hard stratum. An embedded steel pipe is vertically arranged in the reinforced concrete pile; the diameter of the reinforced concrete pile is larger than that of the steel pipe pile, the steel pipe pile is inserted into the lower portion of the reinforced concrete pile through the interior of the embedded steel pipe of the reinforced concrete pile, and the upper end of the steel pipe pile is embedded into the embedded steel pipe. The reinforced concrete piles located on the upper soft stratum and the steel pipe piles located on the lower hard stratum are arranged, the reinforced concrete piles are constructed firstly, then the reinforced concrete piles are inserted into the steel pipe piles, on-site construction noise is low, construction is easy and convenient, pile deviation and pile breaking are not prone to occurring, and the engineering cost is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of support piles, in particular to a spliced pile support system suitable for an upper-soft lower-hard multi-element stratum and a construction method. BACKGROUND

[0002] The upper-soft lower-hard stratum of soil and rock combination, i.e. the geological structure with soil layer in the upper part and rock layer in the lower part, when the soil-rock interface inclination is greater than 15 degrees or there is a soft interlayer, the natural rock mass cannot form a stable arch effect, and the foundation pit / slope stability is insufficient, so the support pile must share the lateral pressure. When adjacent to a subway tunnel or a high-rise building, even a small soil creep can trigger a chain reaction, and the structural load and deformation control requirements are high, so the support pile construction must be carried out. Due to the change of interface hydraulic connection caused by blasting vibration or dewatering, groundwater action is significant, so the support pile construction must be carried out. The upper soft soil layer is usually Quaternary deposits (such as fill, clay, sand), which has low strength and high compressibility, and is prone to lateral deformation. The lower hard rock layer is usually bedrock above medium weathering (such as granite, gneiss), which has high strength but large rock surface undulation, which may cause uneven rock-embedded depth of the pile end.

[0003] The traditional concrete bored pile faces many problems in the construction process of the lower rock layer. First, during pile driving, the vibration generated during construction will cause great disturbance to the surrounding environment and serious noise pollution due to the hard geological conditions of the lower rock layer. Second, the drilling footage is very difficult in this stratum, which seriously affects the construction progress. Third, in this geological condition, the pile hole verticality is not enough due to the over-hard rock layer, which may cause the "deviated pile" phenomenon. At the same time, the thickness of the support pile bottom sediment often exceeds the specified limit. In addition, the drill bit is easily damaged when working in this hard stratum, which increases the risk of "broken pile", undoubtedly increasing the construction cost and uncertainty. When the main structure and the auxiliary structure are combined, the support pile at the main structure and auxiliary structure combination position needs to be removed when the auxiliary foundation pit is excavated. However, due to the use of reinforced concrete support pile, the removal work is extremely difficult, not only time-consuming and labor-intensive, but also significantly increasing the engineering cost.

[0004] Therefore, there is an urgent need for a support system suitable for the upper-soft lower-hard multi-element stratum and its construction method, which has small noise, simple construction, is not prone to pile deviation and pile breakage, and has low engineering cost. SUMMARY

[0005] The purpose of the present application is to provide a spliced pile support system suitable for an upper-soft lower-hard multi-element stratum and a construction method to at least solve the problems of large noise, difficult construction, easy pile deviation and pile breakage, and high engineering cost of the existing support pile construction in the upper-soft lower-hard multi-element stratum.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0007] The application relates to a spliced pile supporting system suitable for a soft-hard multi-layer stratum, which comprises reinforced concrete piles in the upper soft stratum and steel pipe piles in the lower hard stratum.

[0008] A pre-embedded steel pipe is vertically arranged in the reinforced concrete pile.

[0009] The diameter of the reinforced concrete pile is larger than that of the steel pipe pile, the steel pipe pile is inserted into the lower part of the reinforced concrete pile through the pre-embedded steel pipe, and the upper end of the steel pipe pile is embedded into the inside of the pre-embedded steel pipe.

[0010] Further, an outer steel casing is arranged on the periphery of the reinforced concrete pile.

[0011] Further, a steel reinforcement cage is arranged in the inside of the outer steel casing.

[0012] Further, the pre-embedded steel pipe is arranged in the steel reinforcement cage through a support.

[0013] Further, the diameter of the pre-embedded steel pipe is larger than that of the steel pipe pile.

[0014] Further, a corbel is arranged above the reinforced concrete pile.

[0015] Further, the inside of the pre-embedded steel pipe and the steel pipe pile is filled with micro-expanding cement mortar.

[0016] Further, a plurality of supporting anchor cables are arranged on the outside of the reinforced concrete pile at intervals.

[0017] Further, a plurality of supporting anchor rods are arranged on the outside of the steel pipe pile at intervals.

[0018] The application also relates to a spliced pile supporting construction method suitable for a soft-hard multi-layer stratum, and the construction method comprises the following steps.

[0019] The upper reinforced concrete pile is drilled, and the outer steel casing is simultaneously lowered;

[0020] The pre-embedded steel pipe is fixed in the steel reinforcement cage through the support, and then the pre-embedded steel pipe and the steel reinforcement cage are lowered into the outer steel casing;

[0021] The reinforced concrete pile is poured with concrete, and the pre-embedded steel pipe is not poured;

[0022] After the reinforced concrete pile is initially cured, the lower steel pipe pile is drilled along the pre-embedded steel pipe;

[0023] After the drilling construction of the steel pipe pile is completed according to the design elevation, the steel pipe pile is placed in the embedded steel pipe, so that the steel pipe pile is inserted below the reinforced concrete pile;

[0024] Subsequently, the micro-expanding cement mortar is grouted through the embedded steel pipe, so that the micro-expanding cement mortar fills the steel pipe pile and the embedded steel pipe;

[0025] After the design strength is met, excavation work is carried out, and the support anchor cable and the support anchor rod are erected simultaneously during excavation, until the excavation of the foundation pit is completed.

[0026] Compared with the prior art, the beneficial effects of the present application are as follows:

[0027] 1、The present application provides a spliced pile support system and construction method suitable for a soft upper and hard lower multi-element stratum, a reinforced concrete pile located in the upper soft stratum and a steel pipe pile located in the lower hard stratum are provided, the steel pipe pile is arranged below the reinforced concrete pile, and the upper end of the steel pipe pile is embedded in the reinforced concrete pile, by arranging the reinforced concrete pile in the upper soft stratum, the vibration generated during pile driving will not cause great disturbance to the surrounding environment, the noise pollution is small, and the footage is easy when drilling into the stratum, the construction is simple, thereby the construction progress can be accelerated.

[0028] 2、The present application first constructs the reinforced concrete pile, the embedded steel pipe is arranged in the reinforced concrete pile, the drilling construction of the lower steel pipe pile is carried out along the embedded steel pipe, and then the steel pipe pile is inserted through the embedded steel pipe of the reinforced concrete pile, since the embedded steel pipe is vertically arranged, the steel pipe pile can avoid deviation when drilling along the embedded steel pipe, and the steel pipe pile is inserted and arranged, so that the construction is simple, thereby the construction progress is accelerated, and the thickness of the sediment at the bottom of the spliced pile is within the specified limit, and the reinforced concrete pile is located in the upper soft stratum, and the steel pipe pile is inserted into the lower hard stratum through the reinforced concrete pile, so that the risk of broken pile is not easily caused, thereby the increase of construction cost and construction uncertainty are avoided.

[0029] 3、The diameter of the steel pipe pile in the present application is smaller than the diameter of the reinforced concrete pile, when the auxiliary foundation pit is excavated, the steel pipe pile located at the position of the main body and the auxiliary body does not need to be removed, so that the construction is simple, time and labor are saved, the engineering cost is low, the operation adaptability of the present application is high, the economic benefit and social benefit are high, and the present application has a wide application prospect in urban rail transit, railway, building construction and the like. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description only represent some embodiments of the present application, and for those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0031] Fig. 1 is a longitudinal sectional view of the present application;

[0032] Fig. 2 is a transverse sectional view of the present application;

[0033] Fig. 3 is a schematic plan view of the envelope structure of the present application;

[0034] indicated as:

[0035] 1 - reinforced concrete pile, 11 - embedded steel pipe, 12 - outer steel casing, 13 - support anchor, 14 - steel reinforcement cage, 2 - steel pipe pile, 21 - support anchor rod, 3 - micro-expansive cement mortar, 4 - corbel, 5 - steel reinforcement. DETAILED DESCRIPTION

[0036] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0037] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0038] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "setting" should be understood broadly, for example, it can be fixedly connected, set, or detachably connected, set, or integrally connected, set. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0039] In the description of the present invention, it should be understood that multiple steps are involved in the description of the method, which should not be understood as a limitation on the order of the method steps. Technical solutions obtained by simply changing the order of the steps when solving the same technical problem are also within the scope of protection of the present invention.

[0040] Example 1:

[0041] like Figs. 1-3 As shown, this embodiment provides a spliced ​​pile support system suitable for use in multiple strata with soft upper layers and hard lower layers, including reinforced concrete piles 1 located in the upper soft stratum and steel pipe piles 2 located in the lower hard stratum.

[0042] Among them, a crown beam 4 is provided above the reinforced concrete pile 1, the steel pipe pile 2 is provided at the lower end of the reinforced concrete pile 1, and the upper end of the steel pipe pile 2 is embedded in the reinforced concrete pile 1, so that the connection between the reinforced concrete pile 1 and the steel pipe pile 2 is more stable. In this embodiment, the length of the steel pipe pile 2 embedded in the reinforced concrete pile 1 is 2-3m.

[0043] Specifically, an outer steel casing 12 is provided on the outer periphery of the reinforced concrete pile 1. During the construction of the upper reinforced concrete pile 1, the outer steel casing 12 is lowered synchronously while the rotary drilling rig is drilling a hole, thereby preventing the hole from collapsing. Afterwards, a steel cage 14 and embedded steel pipe 11 are placed in the outer steel casing 12.

[0044] A bracket is connected between the steel cage 14 and the embedded steel pipe 11. In this embodiment, the bracket is twelve steel bars 5, which are distributed in three layers and are respectively arranged at the upper, middle and lower parts of the embedded steel pipe 11. Each layer is provided with four steel bars 5. The two ends of the steel bars 5 are welded and fixed to the inner wall of the steel cage 14 and the outer wall of the embedded steel pipe 11, respectively, so as to fix the embedded steel pipe 11 to the steel cage 14 to ensure the verticality of the embedded steel pipe 11 during the later pouring. In other embodiments, the number of steel bars 5 can be determined according to the on-site construction conditions and is not limited to this.

[0045] The embedded steel pipe 11 is vertically penetrated from the top of the crown beam 4 to the bottom of the reinforced concrete pile 1. When drilling the steel pipe pile 2 in the later stage, drilling along the embedded steel pipe 11 can avoid the pile from being offset, and the embedded steel pipe 11 can provide a strength reinforcement for the reinforced concrete pile 1.

[0046] In this embodiment, the diameter of the embedded steel pipe 11 is 350 mm and the wall thickness is 3 mm.

[0047] Specifically, after the embedded steel pipe 11 and the steel cage 14 are fixed, they are lowered together into the outer steel casing 12 , and then the concrete of the upper reinforced concrete pile 1 is poured, while the embedded steel pipe 11 is not poured.

[0048] In the embodiment, the reinforced concrete pile 1 is arranged in the upper soft ground layer, so that the vibration generated during pile driving does not cause great disturbance to the surrounding environment, noise pollution is small, drilling into the ground is easy, and construction is simple, thereby speeding up the construction progress.

[0049] After the reinforced concrete pile 1 is completed and initial setting of concrete pouring, drilling is performed from the middle of the corbel 4 downward, and the steel pipe pile 2 is placed after drilling.

[0050] Specifically, the downhole drill is used to drill the lower steel pipe pile 2 along the embedded steel pipe 11 from the corbel 4, and the downhole drill machine is used to complete the drilling of the lower steel pipe pile 2 according to the design elevation. After the drilling of the lower steel pipe pile 2 is completed, the steel pipe pile 2 is inserted into the embedded steel pipe 11, so that the steel pipe pile 2 is inserted below the reinforced concrete pile 1.

[0051] In the embodiment, the embedded steel pipe 11 is vertically arranged, and the steel pipe pile 2 is drilled along the embedded steel pipe 11 during drilling construction, so that deviation of the pile can be avoided. The steel pipe pile 2 is arranged by insertion, so that the construction is simple, thereby speeding up the construction progress, and the thickness of the sediment at the bottom of the spliced pile is within the specified limit.

[0052] In the embodiment, the reinforced concrete pile 1 is located in the upper soft ground layer, and the steel pipe pile 2 is inserted into the lower hard ground layer through the reinforced concrete pile 1, so that the risk of pile breaking is not easily caused, thereby avoiding the increase of construction cost and construction uncertainty.

[0053] In the embodiment, the hole diameter drilled by the downhole drill is 300 mm, the diameter of the steel pipe pile 2 is 200 mm, and the wall thickness of the steel pipe pile 2 is 6 mm.

[0054] The embedded steel pipe 11 and the steel pipe pile 2 are both filled with micro-expansive cement mortar 3.

[0055] Specifically, the micro-expansive cement mortar 3 is poured through the embedded steel pipe 11, so that the micro-expansive cement mortar 3 fills the steel pipe pile 2 and the embedded steel pipe 11, thereby forming an integral structure of the reinforced concrete pile 1 and the steel pipe pile 2.

[0056] The outer side of the reinforced concrete pile 1 is provided with a plurality of support anchor cables 13, and the outer side of the steel pipe pile 2 is provided with a plurality of support anchor rods 21.

[0057] Specifically, after the micro-expansive cement mortar 3 is filled to meet the design strength, excavation is performed, and slope support is simultaneously performed during the excavation process, that is, the support anchor cables 13 and the support anchor rods 21 are erected during excavation, until the excavation of the foundation pit is completed.

[0058] In the embodiment, since the diameter of the steel pipe pile 2 is smaller than the diameter of the reinforced concrete pile 1, when the auxiliary foundation pit is excavated, the steel pipe pile 2 located at the position of the main body and the auxiliary body does not need to be removed, thereby making the construction simple, saving time and effort, and reducing the engineering cost.

[0059] Embodiment 2

[0060] The embodiment provides a spliced pile supporting construction method suitable for a soft upper and hard lower multi-element stratum, and steps are as follows:

[0061] S1: first, the upper reinforced concrete pile 1 is constructed:

[0062] S11: during the construction process, the outer steel casing 12 is synchronously followed and lowered during the drilling of the rotary drilling rig, so as to avoid hole collapse;

[0063] S12: the embedded steel pipe 11 is welded and fixed with the steel reinforcement cage 14 through the steel reinforcement 5, and then the embedded steel pipe 11 and the steel reinforcement cage 14 are lowered in the outer steel casing 12;

[0064] S13: after the steel reinforcement cage 14 and the embedded steel pipe 11 are placed, the concrete pouring of the upper reinforced concrete pile 1 is performed, and the embedded steel pipe 11 is not poured.

[0065] S2: then, the lower steel pipe pile 2 is constructed:

[0066] S21: after the upper reinforced concrete pile 1 is initially cured, the down-the-hole drill is used to perform the drilling construction of the lower steel pipe pile 2 along the embedded steel pipe 11 from the corbel 4;

[0067] S22: after the drilling construction of the lower steel pipe pile 2 is completed by the down-the-hole drill according to the design elevation, the steel pipe pile 2 is inserted into the embedded steel pipe 11, so that the steel pipe pile 2 is inserted below the reinforced concrete pile 1, and the upper end of the steel pipe pile 2 is inserted into the reinforced concrete pile 1;

[0068] S23: then, the micro-expanding cement mortar 3 is grouted through the embedded steel pipe 11, so that the micro-expanding cement mortar 3 fills the steel pipe pile 2 and the embedded steel pipe 11;

[0069] S24: after the design strength is met, the excavation operation is performed, and in the excavation process, the slope supporting is synchronously performed, that is, the supporting anchor cable 13 and the supporting anchor rod 21 are erected while excavating, until the excavation of the foundation pit is completed.

[0070] The splicing pile supporting system construction method suitable for the upper-soft and lower-hard multi-element stratum sets the reinforced concrete pile in the upper soft stratum and the steel pipe pile in the lower hard stratum, the upper end of the steel pipe pile is embedded into the reinforced concrete pile, the reinforced concrete pile is arranged in the upper soft stratum, so that the vibration generated during pile driving does not cause great disturbance to the surrounding environment, the noise pollution is small, and the footage is easy when drilling into the stratum, the construction is simple, thereby the construction progress can be accelerated. In addition, the reinforced concrete pile is constructed first, the embedded steel pipe is arranged in the reinforced concrete pile, the drilling construction of the lower steel pipe pile is carried out along the embedded steel pipe, and then the steel pipe pile is inserted through the embedded steel pipe of the reinforced concrete pile. Since the embedded steel pipe is vertically arranged, the steel pipe pile drilling construction can avoid pile deviation when drilling along the embedded steel pipe, and the steel pipe pile is inserted and arranged, so that the construction is simple, thereby the construction progress is accelerated, the thickness of the sediment at the bottom of the splicing pile is within the specified limit, the reinforced concrete pile is arranged in the upper soft stratum, and the steel pipe pile is inserted into the lower hard stratum through the reinforced concrete pile, so that the risk of pile breaking is not easy to cause, thereby the increase of construction cost and construction uncertainty are avoided. In addition, the diameter of the steel pipe pile is smaller than that of the reinforced concrete pile, when the auxiliary foundation pit is excavated, the steel pipe pile at the position of the main body and the auxiliary combination does not need to be removed, so that the construction is simple, time and labor are saved, the engineering cost is low, the operation adaptability of the present application is high, the economic benefit and social benefit are high, and the present application has a wide application prospect in urban rail transit, railway, building construction and other engineering.

[0071] The above application of specific examples to the present application is only used to help understand the present application and does not limit the present application. For those skilled in the art to which the present application belongs, according to the idea of the present application, several simple deductions, deformations or substitutions can be made.

Claims

1. Applicable to the spliced ​​pile support system under multiple strata with soft upper layer and hard lower layer, characterized by: It comprises a reinforced concrete pile (1) located in an upper soft stratum and a steel pipe pile (2) located in a lower hard stratum; A pre-buried steel pipe (11) is vertically arranged in the reinforced concrete pile (1); The diameter of the reinforced concrete pile (1) is greater than the diameter of the steel pipe pile (2); the steel pipe pile (2) is inserted below the reinforced concrete pile (1) through the embedded steel pipe (11) of the reinforced concrete pile (1), and the upper end of the steel pipe pile (2) is embedded in the embedded steel pipe (11).

2. The spliced ​​pile support system suitable for use in multiple strata with soft upper and hard lower layers according to claim 1 is characterized by: An outer steel casing (12) is provided on the outer periphery of the reinforced concrete pile (1).

3. The spliced ​​pile support system suitable for use in multiple strata with soft upper and hard lower layers according to claim 2 is characterized by: A steel cage (14) is provided inside the outer steel casing (12).

4. The spliced ​​pile support system suitable for use in multiple strata with soft upper and hard lower layers according to claim 3 is characterized by: The embedded steel pipe (11) is arranged in the steel cage (14) via a bracket.

5. The spliced ​​pile support system suitable for use in multiple strata with soft upper and hard lower layers according to claim 1 is characterized by: The diameter of the embedded steel pipe (11) is greater than the diameter of the steel pipe pile (2).

6. The spliced ​​pile support system suitable for use in multiple strata with soft upper and hard lower layers according to claim 1 is characterized by: A cap beam (4) is provided above the reinforced concrete pile (1).

7. The spliced ​​pile support system suitable for use in multiple strata with soft upper and hard lower layers according to claim 1 is characterized by: The interiors of the embedded steel pipe (11) and the steel pipe pile (2) are both filled with micro-expansion cement mortar (3).

8. The spliced ​​pile support system suitable for use in multiple strata with soft upper and hard lower layers according to claim 1 is characterized by: A plurality of supporting anchor cables (13) are arranged at intervals outside the reinforced concrete pile (1).

9. The spliced ​​pile support system suitable for use in multiple strata with soft upper and hard lower layers according to claim 1 is characterized by: A plurality of support anchor rods (21) are arranged at intervals outside the steel pipe pile (2).

10. A spliced ​​pile support construction method suitable for use in multiple strata with soft upper and hard lower layers, characterized by: The construction method steps are as follows: Drilling the upper reinforced concrete pile (1) and simultaneously lowering the outer steel casing (12); The embedded steel pipe (11) is fixed in the steel cage (14) through the bracket, and then the embedded steel pipe (11) and the steel cage (14) are lowered into the outer steel casing (12); Concrete is poured into the reinforced concrete pile (1), but no concrete is poured into the embedded steel pipe (11); After the reinforced concrete pile (1) is initially set, drilling of the lower steel pipe pile (2) is performed along the pre-buried steel pipe (11); After completing the drilling construction of the steel pipe pile (2) according to the designed elevation, the steel pipe pile (2) is placed in the embedded steel pipe (11) so that the steel pipe pile (2) is inserted below the reinforced concrete pile (1); Then, the micro-expansive cement mortar (3) is poured through the pre-buried steel pipe (11), so that the micro-expansive cement mortar (3) fills the steel pipe pile (2) and the pre-buried steel pipe (11); After the design strength is met, excavation is carried out and slope support is carried out simultaneously, and the support anchor cables (13) and the support anchor rods (21) are set up while excavating until the foundation pit excavation is completed.

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