Drainage method in ballast backfill body on deep covering layer side slope

Abstract

The invention discloses a drainage method for a ballast backfill body on a deep and thick covering layer side slope, which comprises the following steps of: cleaning a foundation along the original earth surface of the side slope for 1-2m thick, excavating steps which are inclined inwards by 2-5% along the slope in the foundation cleaning process, and controlling the width of the steps according to 2-8m; horizontally paving the ballasts in a layering manner according to a layer of 30-50cm, and compacting the ballasts; a trapezoidal groove is dug in the compacted ballast surface, and a fine sand cushion layer with the thickness of 5-10 cm is laid; drainage steel floral tubes are laid on the fine sand cushion layer, the horizontal distance between the drainage steel floral tubes on the steps is 5-10 m, and the drainage steel floral tubes incline towards the outer side of the backfill body by 1-3%; the fine sand continues to be backfilled till the trapezoidal groove is filled; and the steps are repeated, a layer of drainage steel floral tubes is arranged every 2-4 stages of excavation steps, and if the backfill body is provided with multiple stages of side slopes, it is guaranteed that each stage of backfill side slope is provided with at least one layer of drainage steel floral tubes. By means of the drainage steel floral tubes laid in the ballast backfill body, seepage water in the backfill body can be rapidly drained, the construction period is greatly shortened, and the construction efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of slope drainage systems in the civil engineering industry, and in particular relates to a drainage method in a ballast backfill body on a thick overburden slope. Background Art

[0002] The existing slope drainage methods are mainly surface drainage and underground drainage. Slope drainage mostly uses intercepting ditches and drainage ditches. To discharge the seepage inside the slope, underground drainage methods need to be used. Underground drainage uses seepage ditches, inclined drainage holes and other methods.

[0003] In the underground drainage methods recommended in the existing specifications "Technical Specifications for Building Slope Engineering" (GB 50330-2013) and "Specifications for Slope Design of Hydropower Engineering" (NB / T 10512-2021), the seepage ditch needs to be equipped with a filter layer on the top and side walls, a sealing layer at the bottom, and the base should be set on a relatively solid soil layer below the aquifer. For the backfill body on the deep cover layer, there is a risk of collapse and blockage, which increases the project investment and construction difficulty, and also prolongs the construction period. The inclined drainage hole needs to be drilled on the slope first, and then the drainage pipe is installed. The drilling depth is limited by the capacity of the drilling rig. For the backfill slope, the hole is easy to collapse after drilling and it is difficult to form a hole. The inclined drainage hole is not only difficult to construct, but also difficult to effectively play the drainage effect.

[0004] In mountainous terrain, when it is difficult to find a large enough site to arrange buildings, a combination of slope excavation and backfilling is often used to expand the site. When backfilling on a thick cover layer, the overall slope stability requirements of the thick cover layer and the ballast backfill body must be met. Rainfall seepage into the backfill body and the cover layer will cause the shear parameters to decrease, which will have an adverse effect on slope stability. It is very important to take effective methods to discharge the seepage water in the slope and reduce the pore water pressure. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a drainage method for ballast backfill on the slope of a thick covering layer, which can more effectively discharge the seepage water inside the ballast backfill, reduce the pore water pressure, and reduce the infiltration of precipitation into the thick covering layer and the ballast backfill, which is beneficial to improving the overall stability of the thick covering layer and the ballast backfill.

[0006] The present invention is achieved by a method for draining water from a ballast backfill body on a thick overburden slope, comprising the following steps:

[0007] Step 1: clear the original surface of the slope with a thickness of 1 to 2 meters. During the clearing process, dig steps with a slope of 2 to 5% inwards. The width of the steps is controlled at 2 to 8 meters.

[0008] Step 2: Spread and compact the ballast in 30-50 cm layers horizontally;

[0009] Step 3: dig a trapezoidal groove on the compacted ballast surface and lay a 5-10 cm thick fine sand cushion layer;

[0010] Step 4: laying drainage steel pipes on the fine sand cushion layer, with the horizontal spacing of the drainage steel pipes on the steps being 5 to 10 m and tilted 1 to 3% toward the outside of the backfill body;

[0011] Step 5, continue to backfill the fine sand until the trapezoidal groove is filled;

[0012] Step 6, repeat steps 2 to 5, and set a layer of drainage steel pipe for every 2 to 4 excavation steps. If the backfill body is set with multiple slopes, ensure that each level of backfill slope has at least one layer of drainage steel pipe.

[0013] The drainage steel flower pipe is covered with non-woven geotextile.

[0014] The invention has the advantages and technical effects that the drainage steel flower pipes laid inside the ballast backfill body can be used to quickly drain the seepage water in the backfill body, which greatly saves the construction period and improves the construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a longitudinal section view of the arrangement of drainage steel flower pipes in the ballast backfill body on the thick overburden layer of the present invention;

[0016] Figure 2 It is a cross-sectional view of the arrangement of drainage steel flower pipes in the ballast backfill body on the thick overburden layer of the present invention;

[0017] Figure 3 It is a plan view of the arrangement of drainage steel pipes in the ballast backfill body on the thick overburden layer of the present invention;

[0018] Figure 4 This is a practical application diagram of the arrangement of drainage steel flower pipes in the ballast backfill body on the thick overburden layer of the present invention.

[0019] In the figure, 1 is the drainage steel pipe; 2 is the step for clearing the surface; 3 is the ballast backfill area; 4 is the trapezoidal groove; 5 is the fine sand; 6 is the boundary line between the two layers of ballast backfill; 7 is the original soil; 8 is the mortared stone facing. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation methods described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by terms such as “upper”, “middle”, “lower”, “inside”, “outside”, and “both sides” are based on the orientations or positional relationships shown in the accompanying drawings, and are only simplified descriptions for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0022] like Figure 1-3 As shown, the drainage method in the ballast backfill body on the thick overburden slope of the present invention comprises the following steps:

[0023] Step 1: clear the original surface of the slope with a thickness of 1 to 2 meters. During the clearing process, dig steps with a slope of 2 to 5% inwards. The width of the steps is controlled at 2 to 8 meters.

[0024] Step 2: Spread and compact the ballast in 30-50 cm layers horizontally;

[0025] Step 3: dig a trapezoidal groove on the compacted ballast surface and lay a 5-10 cm thick fine sand cushion layer;

[0026] Step 4: laying drainage steel pipes on the fine sand cushion layer, with the horizontal spacing of the drainage steel pipes on the steps being 5 to 10 m and tilted 1 to 3% toward the outside of the backfill body;

[0027] Step 5, continue to backfill the fine sand until the trapezoidal groove is filled;

[0028] Step 6, repeat steps 2 to 5, and set a layer of drainage steel pipe for every 2 to 4 excavation steps. If the backfill body is set with multiple slopes, ensure that each level of backfill slope has at least one layer of drainage steel pipe.

[0029] The drainage steel flower pipe is covered with non-woven geotextile.

[0030] like Figure 4 As shown, the drainage method in the ballast backfill body on the thick overburden slope according to the embodiment of the present invention comprises the following steps:

[0031] Step 1: Clear the foundation along the original surface with a thickness of 1m. During the clearing process, dig steps with a slope of 4% inward. The width of the steps is controlled at 4m, and can be appropriately increased in areas with gentle original terrain;

[0032] Step 2: Spread the ballast in 40 cm layers horizontally and compact it;

[0033] Step 3: dig a trapezoidal groove on the compacted ballast surface and lay a fine sand cushion layer with a thickness of half the diameter of the drainage steel pipe;

[0034] Step 4: Lay drainage steel pipes on the fine sand cushion layer. The horizontal spacing of the drainage steel pipes on the steps is 8m, and they are inclined 1% toward the outside of the backfill body.

[0035] Step 5, continue to backfill the fine sand until the trapezoidal groove is filled;

[0036] Step 6, repeat steps 2 to 5, set up a layer of drainage steel pipes for every 3 excavation steps, and ensure that each level of fill slope has at least one layer of drainage steel pipes.

[0037] In the present invention, 1. The step that is inclined inward by 4% is beneficial to the stability of the backfill body on the one hand, and on the other hand, the permeability of the ballast is relatively large, while the permeability of the covering layer is relatively small, and the joint surface is relatively impermeable. The inward inclination of the step can collect the seepage water to the inside of the step, and then discharge it to the outside of the backfill body by burying the drainage steel pipe. 2. The trapezoidal groove is used to lay the drainage steel pipe to avoid damage to the steel pipe during the rolling of the upper ballast. 3. The fine sand cushion layer is used to level the bottom of the excavated trapezoidal groove to avoid uneven force on the steel pipe during the rolling of the upper ballast. After laying the drainage steel pipe, continue to backfill the fine sand to protect the steel pipe to avoid direct contact between the steel pipe and the upper layer of rolled ballast, causing deformation and damage to the steel pipe. 4. The function of the drainage steel pipe is to discharge the seepage water in the backfill body to the outside of the backfill body, and the function of the non-woven geotextile is to avoid clogging of the drainage steel pipe.

[0038] The method of the present invention effectively discharges seepage water in the backfill body, reduces the amount of water infiltrating into the covering layer, reduces the pore water pressure, improves the stability of the slope, and solves the problems that the construction procedure of the seepage ditch is complicated and there is a risk of collapse and blockage; the depth of the drainage hole is limited by the drilling rig capacity and the hole is prone to collapse. It has the advantages of simple construction and shortened construction period.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for draining ballast backfill on a thick overburden slope, characterized in that: The following steps are involved: Step 1: clear the original surface of the slope with a thickness of 1 to 2 meters. During the clearing process, dig steps with a slope of 2 to 5% inwards. The width of the steps is controlled at 2 to 8 meters. Step 2: Spread and compact the ballast in 30-50 cm layers horizontally; Step 3: dig a trapezoidal groove on the compacted ballast surface and lay a 5-10 cm thick fine sand cushion layer; Step 4: laying drainage steel pipes on the fine sand cushion layer, with the horizontal spacing of the drainage steel pipes on the steps being 5 to 10 m and tilted 1 to 3% toward the outside of the backfill body; Step 5, continue to backfill the fine sand until the trapezoidal groove is filled; Step 6, repeat steps 2 to 5, and set a layer of drainage steel pipe for every 2 to 4 excavation steps. If the backfill body is set with multiple slopes, ensure that each level of backfill slope has at least one layer of drainage steel pipe.

2. The drainage method in the ballast backfill on the thick overburden slope according to claim 1 is characterized in that: The drainage steel flower pipe is covered with non-woven geotextile.

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