Calculation method of RJP water-stop curtain radius for pile-hole station in water-rich strata

Abstract

The present invention provides a method for calculating the radius of the RJP water-stop curtain for a station using the pile method in a water-rich stratum. An RJP rotary jet pile is arranged between two adjacent cast-in-place piles. The RJP rotary jet pile overlaps the cast-in-place piles on both sides to form a water-stop curtain. The center of the RJP rotary jet pile is equidistant from the center of the cast-in-place piles on both sides. The center of the RJP rotary jet pile is on a straight line with the center of the cast-in-place piles on both sides. The calculation formula for the minimum radius of the RJP rotary jet pile is as follows: In the above formula, r is the minimum radius of the rotary jet pile, in m; R is the radius of the cast-in-place pile, in m; L is the minimum overlap arc length of the rotary jet pile, in m; S is the distance between two adjacent cast-in-place piles, in m. The present invention reduces the amount of water-stop materials used and reduces costs while ensuring the water-stop effect of the underground excavation station.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and in particular relates to a method for calculating the radius of an RJP water-stop curtain suitable for a tunnel pile method station in a water-rich stratum. Background Art

[0002] At present, due to the continuous development of urban space and the continuous improvement of infrastructure, ground transportation, pipelines, and buildings have become important factors restricting traditional subway construction. Therefore, the use of the pile method for underground excavation of subway stations has become a future development trend. In the sand and gravel stratum, the permeability coefficient is large, the construction risk is high, the difficulty is high, and the cost is high. The traditional water-stop curtain overlap method is difficult to achieve a good water-stop effect. Therefore, it is necessary to improve the water-stopping technology in the underground excavation station tunnel, adjust the water-stop curtain overlap method, and ensure the water-stopping effect. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a method for calculating the radius of the RJP water-stop curtain applicable to a tunnel pile method station in water-rich strata, which ensures the water-stopping effect of the underground excavation station while reducing the amount of water-stopping materials used and lowering costs.

[0004] In order to achieve the above purpose, the technical solution adopted by the embodiment of the present invention is as follows:

[0005] The embodiment of the present invention provides a method for calculating the radius of an RJP water-stop curtain for a station using the pile method in a water-rich stratum. An RJP rotary jet pile is arranged between two adjacent cast-in-place piles. The RJP rotary jet pile is overlapped with the cast-in-place piles on both sides to form a water-stop curtain. The center of the RJP rotary jet pile is equidistant from the center of the cast-in-place piles on both sides. The center of the RJP rotary jet pile is in a straight line with the center of the cast-in-place piles on both sides. The calculation formula for the minimum radius of the RJP rotary jet pile is as follows:

[0006]

[0007] In the above formula, r-RJP minimum radius of jet grouting pile, unit: m;

[0008] R-radius of cast-in-place pile, unit: m;

[0009] L-RJP rotary jet grouting pile minimum lap arc length, unit: m;

[0010] S-the distance between two adjacent cast-in-place piles, unit: m.

[0011] As a preferred method, the minimum lap arc length of the RJP jet grouting piles required for water stopping is determined according to the geological conditions in the project.

[0012] Preferably, it is suitable for RJP jet grouting piles with a pile diameter of 0.6-1.5m.

[0013] The present invention has the following beneficial effects:

[0014] The present invention provides a method for calculating the radius of an RJP water-stop curtain applicable to a tunnel pile method station in a water-rich stratum. When constructing a tunnel pile method station in a water-rich stratum, the water-stopping effect of the water-stop curtain can be guaranteed, thereby ensuring construction safety.

[0015] Water seepage generally occurs at the bite position between piles. The edge length of the bite body between piles is calculated based on the principle that the seepage force is inversely proportional to the length of the seepage path. The longer the seepage path, the better the water-stopping effect. After determining the minimum overlap arc length required for water-stopping according to geology in the project, the minimum radius of the RJP jet grouting pile can be calculated by the formula provided by the present invention, thereby reducing the amount of water-stopping materials and reducing costs while ensuring the water-stopping effect of the underground excavation station.

[0016] The invention is simple to construct, does not increase the work difficulty of technical personnel during construction, and has good feasibility. The invention studies a more reasonable overlapping method through in-depth analysis of the overlapping method of the RJP water-stop curtain, and its application scope includes but is not limited to pile-hole stations in water-rich strata, which ensures the water-stopping effect and has good social and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of the present invention.

[0018] Figure 1 It is a schematic diagram of the overlap design structure of the RJP water-stop curtain according to an embodiment of the present invention.

[0019] Description of reference numerals:

[0020] 1. Cast-in-place piles; 2. RJP jet jet piles. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] The present embodiment provides a method for calculating the radius of the RJP water-stop curtain for a tunnel pile method station in water-rich strata. The water-stop curtain is constructed by using RJP in the tunnel. When factors such as the diameter of the cast-in-place piles, the distance between the pile centers, and the amount of water-stop material between the piles (i.e., the cross-sectional area of ​​the water-stop material) are the same, the lap arc length of the cast-in-place pile 1 and the RJP rotary jet pile 2 is first calculated.

[0023] like Figure 1As shown, a RJP rotary jet pile 2 is set between two adjacent cast-in-place piles 1. The RJP rotary jet pile 2 overlaps with the cast-in-place piles 1 on both sides to form a water-stop curtain. The distance between the center of the RJP rotary jet pile 2 and the center of the cast-in-place piles 1 on both sides is equal. Assuming the radius of the cast-in-place pile 1 is R, the distance between the two adjacent cast-in-place piles 1 is S, and the radius of the RJP rotary jet pile 2 is r. When the area of ​​the RJP rotary jet pile 2 is constant, the radius r is a constant, and the overlap arc length of the single-sided RJP rotary jet pile is L = αR, α is the center angle, and in ΔAO1O3, there is the following relationship:

[0024]

[0025] The center O3 of the RJP jet grouting pile can move up and down the center line. Assuming the coordinates of O3 are (0, h), the coordinates of the centers of the two sides of the cast-in-place pile are O1 coordinates respectively. O2 coordinates but Then the function of the overlapping arc length L and h is:

[0026]

[0027] By calculation, when h is 0, the overlap arc length L is the longest. Therefore, when the three centers (O1, O2, O3) are on the same straight line, the overlap arc length L of the RJP jet grouting pile is the longest.

[0028] Since the seepage force is inversely proportional to the seepage path length (lap arc length), the longer the seepage path, the better the water stopping effect. Therefore, in this embodiment, the center of the RJP jet grouting pile 2 is in a straight line with the center of the cast-in-place piles 1 on both sides.

[0029] The calculation formula of the minimum radius of RJP jet grouting pile can be obtained by reverse calculation as follows:

[0030]

[0031] In the above formula: r is the minimum radius of RJP rotary grouting pile, unit: m; R is the radius of cast-in-place pile, unit: m; L is the minimum lap arc length of RJP rotary grouting pile, unit: m; S is the distance between two adjacent cast-in-place piles, unit: m.

[0032] In this embodiment, a φ1000mm cast-in-place pile 1 is used, the pile spacing between two adjacent cast-in-place piles 1 is 1250mm, and a rotary jet grouting pile 2 is installed in the middle to form a water-stop curtain. When the center of the cast-in-place pile 1 is in the same straight line as the center of the RJP rotary jet grouting pile 2, the lap arc length of the RJP rotary jet grouting pile is the longest.

[0033] The minimum overlap arc length of the RJP jet grouting piles required for water stopping is determined according to the geological conditions in the project. According to the engineering geological conditions of this embodiment, when the minimum overlap arc length of the RJP jet grouting piles (the minimum overlap arc length required for single-sided water stopping) L = 650mm, the water stopping effect of the permeability coefficient less than 0.001m / d that meets the engineering requirements can be achieved. Therefore, the minimum overlap arc length L of the RJP jet grouting piles in this embodiment is 650mm.

[0034] Therefore, the minimum radius of RJP jet grouting piles required for water stopping is derived: the minimum lap arc length of RJP jet grouting piles R=500mm, so α=74°, then in ΔAO1O3, the length of AO3 is the radius r of the RJP jet grouting pile. Since AO1=500mm, According to the law of cosines:

[0035] |AO3| 2 =|AO1| 2 +|O1O3| 2 -2|AO1||O1O3|cos∠AO1O3,

[0036] Then the required AO3=376mm, that is, the minimum radius of RJP rotary jet pile required to achieve water-stopping effect is r=376mm.

[0037] It can be seen from the above technical solutions that the calculation method of the radius of the RJP water-stop curtain applicable to the water-rich stratum pile-hole method station provided in this embodiment can ensure the water-stopping effect of the water-stop curtain and ensure the safety of construction when the water-rich stratum pile-hole method station is constructed. Water seepage generally occurs at the bite position between piles. The principle that the seepage force is inversely proportional to the length of the seepage path is used to calculate the edge length of the bite body between piles and piles, and use it as the length of the seepage path. The longer the seepage path, the better the water-stopping effect. After determining the minimum overlap arc length required for water-stopping according to geology in the project, the minimum radius of the RJP rotary jet pile can be calculated by the formula provided by the present invention, which can reduce the amount of water-stopping materials and reduce costs while ensuring the water-stopping effect of the underground excavation station. This embodiment is simple to construct, does not increase the work difficulty of technicians during construction, and has good feasibility; through an in-depth analysis of the overlap method of the RJP water-stop curtain, a more reasonable overlap method is studied, and the scope of application includes but is not limited to the water-rich stratum pile-hole method station, which ensures the water-stopping effect and has good social and economic benefits.

[0038] The above embodiments of the present invention are described in detail through examples, but the contents described are only exemplary embodiments of the embodiments of the present invention and cannot be considered to limit the scope of implementation of the embodiments of the present invention. The protection scope of the embodiments of the present invention is defined by the claims. Anyone who utilizes the technical solutions described in the embodiments of the present invention, or who, inspired by the technical solutions of the embodiments of the present invention, designs similar technical solutions within the essence and protection scope of the embodiments of the present invention to achieve the above technical effects, or who makes equal changes and improvements to the scope of application, shall still fall within the scope of protection covered by the patent of the embodiments of the present invention.

Claims

1. A method for calculating the radius of RJP water-stop curtain applicable to a station using the pile method in a water-rich stratum, characterized in that: An RJP rotary jet pile is set between two adjacent cast-in-place piles. The RJP rotary jet pile overlaps the cast-in-place piles on both sides to form a water-stop curtain. The center of the RJP rotary jet pile is equidistant from the center of the cast-in-place piles on both sides, and the center of the RJP rotary jet pile is on a straight line with the center of the cast-in-place piles on both sides. The calculation formula for the minimum radius of the RJP rotary jet pile is as follows: In the above formula, r-RJP minimum radius of jet grouting pile, unit: m; R-radius of cast-in-place pile, unit: m; L-RJP rotary jet grouting pile minimum lap arc length, unit: m; S-the distance between two adjacent cast-in-place piles, unit: m.

2. The method for calculating the radius of the RJP water-stop curtain applicable to a station using the pile method in a water-rich stratum according to claim 1 is characterized in that: In the project, the minimum lap arc length of the RJP jet grouting piles required for water stopping is determined based on the geological conditions.

3. The method for calculating the radius of the RJP water-stop curtain applicable to a station using the pile method in a water-rich stratum according to claim 1 is characterized in that: Suitable for RJP jet grouting piles with a pile diameter of 0.6-1.5m.

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