CN111206563A

CN111206563A - Slope siphon drainage device with composite pipe diameter

Info

Publication number: CN111206563A
Application number: CN202010044756.1A
Authority: CN
Inventors: 郑俊; 孙红月; 郭吉超; 吕庆; 王炯超
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2020-01-15
Filing date: 2020-01-15
Publication date: 2020-05-29

Abstract

The invention relates to the field of geotechnical engineering, in particular to a siphon drainage device for a slope with a composite pipe diameter. Comprises a drain pipe and a water injection device; the drain pipe is of a sleeve structure and comprises an external outer drain pipe, and a plurality of inner drain pipes are arranged in the outer drain pipe; the water outlet of the drain pipe is connected with water injection equipment. The invention has the advantages that firstly, the hydraulic radius is increased, and the drainage efficiency is improved; secondly, under the condition of guaranteeing the same hydraulic radius, the installation times of using the composite pipe diameter can be reduced by 4.7 times, and the installation workload is greatly reduced.

Description

Slope siphon drainage device with composite pipe diameter

Technical Field

The invention relates to the field of geotechnical engineering, in particular to a drainage disposal device suitable for slope deformation and damage influenced by underground water action.

Background

The deformation and destruction of the slope is often related to the surface and groundwater activity, where many slope instabilities are directly initiated by the elevation of groundwater. The side slope drainage can improve the shear strength of the slipband soil and reduce the landslide thrust, thereby improving the stability of the side slope.

The main drainage measures of the current side slope are as follows: the underground drainage hole is high in cost and complex in construction process, the horizontal drainage hole is easy to block and poor in drainage effect, the water collection well needs power and frequent management for pumping water, and the ground surface drainage ditch and the drainage blind ditch can only drain shallow water and are poor in effect of improving the stability of the side slope.

Siphon is a physical phenomenon that liquid is pushed to flow by the action force of liquid level height difference, the flow process and flow rate of the siphon are automatically controlled by the change of the liquid level, the siphon is very suitable for the requirement of slope drainage, and the siphon is popularized and applied to slope drainage. In the siphon drainage system, in order to enhance the long-term maintenance-free stability of the system and avoid using a large-pipe-diameter drainage pipe which is difficult to maintain stably for a long time due to accumulation of bubbles, a siphon drainage system with a small pipe diameter (less than or equal to 5mm) is generally adopted. The drainage pipe with small pipe diameter has the big defect of low drainage efficiency, so that in the application process of slope drainage, a large number of siphons are required to be laid, and hundreds of siphons or even thousands of siphons are required, so that a great amount of time is required for finishing the laying of all siphons in a slope siphon drainage project.

Disclosure of Invention

The invention aims to overcome the defects of complicated construction procedures and low drainage efficiency of the traditional single-pipe-diameter siphon drainage system, and provides a slope siphon drainage device with a composite pipe diameter, which can increase the area of a water passing section and improve the drainage efficiency of a siphon pipe on one hand; and meanwhile, the installation times of the siphon drain pipe can be reduced.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the side slope siphon drainage device with the composite pipe diameter comprises a drainage pipe and water injection equipment;

the drain pipe is of a sleeve structure and comprises an external outer drain pipe, and a plurality of inner drain pipes are arranged in the outer drain pipe; the water outlet of the drain pipe is connected with water injection equipment.

As an improvement, the outer drainage pipe is a drainage pipe with the wall thickness of 3mm and the inner diameter of 17 mm.

As an improvement, the inner drainage pipe is a drainage pipe with the wall thickness of 1.5mm and the inner diameter of 5 mm.

As an improvement, three inner drainage pipes are arranged in the outer drainage pipe.

The hydraulic radius R is an important index for measuring the water delivery capacity of the pipeline, and the concrete expression formula is as follows:

R＝A/χ

in the formula, A is the area of the flow cross section; chi is the perimeter of the flow section where the fluid contacts the solid wall, called the wetted perimeter.

For the drainage pipe with composite pipe diameter, the water passing section of the drainage pipe is composed of seven independent sections, namely, the drainage pipe is divided into three types of sections, the hydraulic radius of the drainage pipe is calculated by superposing the sections, the comprehensive hydraulic radius is called, and the concrete solution is shown as the following formula:

for a single 5mm id drain, the hydraulic radius is 1.25, while the hydraulic radius for the composite pipe diameter is about 4.7 times the single pipe diameter.

Compared with the prior art, the invention has the beneficial effects that:

compared with the traditional single drainage pipe with the inner diameter of 5mm, the slope siphon drainage system with the composite pipe diameter has the advantages that the comprehensive hydraulic radius of the composite drainage pipe is about 4.7 times of the hydraulic radius, so that the hydraulic radius is increased, and the drainage efficiency is improved; secondly, under the condition of guaranteeing the same hydraulic radius, the installation times of using the composite pipe diameter can be reduced by 4.7 times, and the installation workload is greatly reduced. On the other hand, compared with a drain pipe with the wall thickness of 1.5mm and the inner diameter of 5mm, the large pipe with the wall thickness of 3mm can effectively prevent air from permeating, so that the influence of air accumulation on the flow speed can be weakened; if a single drain pipe with the same wall thickness of 3mm and the same inner diameter of 5mm is adopted, the composite pipe diameter is adopted to save more materials under the condition of ensuring the same water passing section area.

Drawings

FIG. 1 is a schematic cross-sectional view of a composite diameter drain pipe of the present invention;

FIG. 2 is a schematic diagram of the comprehensive hydraulic radius solving of the composite pipe diameter drain pipe of the present invention;

FIG. 3 is a simplified schematic diagram of the composite pipe diameter siphon drainage apparatus according to the present invention.

In the figure: 1-drilling, 2-slope surface, 3-outer pipe, 4-inner pipe and 5-water collecting tank.

Detailed Description

The following detailed description of the present invention, taken in conjunction with the accompanying drawings, will provide those skilled in the art with a more complete understanding of the present invention, and is not intended to limit the invention in any way.

As shown in fig. 1, a cross-sectional schematic view of a siphon drainage device drain pipe with a composite pipe diameter comprises a drain pipe and water injection equipment; the drain pipe is of a sleeve structure and comprises an external outer drain pipe 3, and three inner drain pipes 4 are arranged in the outer drain pipe 3; and the water outlet of the drain pipe is connected with water injection equipment. The outer pipe 3 is a drain pipe with the wall thickness of 3mm and the inner diameter of 17mm, and the inner pipe 4 of the inner sleeve is 1.5mm in wall thickness and 5mm in inner diameter. And in the process of discharging the underground water in the slope, the underground water level is reduced, when the lift exceeds the water column height corresponding to the local atmospheric pressure, the siphon is temporarily stopped, when the rainfall occurs again, the underground water level in the slope is raised, the siphon action is started again, and the processes are circularly generated.

As shown in fig. 2, the water passing section of the composite pipe diameter drain pipe is composed of seven sections independent from each other, and can be divided into three types, i.e., type i, type ii, and type iii, the comprehensive hydraulic radius of the composite pipe diameter is formed by overlapping the sections, and the concrete solution is as follows:

for a cross-section of type i,

for a type ii cross-section,

for type III cross-sections, R₃＝3×1.25＝3.75

So the comprehensive hydraulic radius of the composite pipe diameterΣR＝R₁+R₂+R₃＝5.86。

The single drain pipe with the inner diameter of 5mm is also a type II section in the drain pipe with the composite pipe diameter, the hydraulic radius is 1.25, and the comprehensive hydraulic radius of the composite pipe diameter is about 4.7 times of the single pipe diameter.

The invention relates to a slope siphon drainage device with composite pipe diameter, which is implemented by the following steps in combination with the attached figure 3:

(1) and acquiring engineering geological conditions of the side slope. Mastering rock-soil body properties and rock-soil combination characteristics of the side slope, mainly researching the relation between underground water and the stability of the side slope, and analyzing the influence of the change of the underground water level on the stability of the side slope.

(2) Design and placement of the bore. According to the form and scale of the landslide, the positions and the number of the declined drill holes 1 are determined on the slope surface 2 needing water drainage, and the inclination angle and the hole depth of the drill holes 1 are determined according to the control requirement of the underground water level of the slope body. The drill hole 1 is formed by drilling with a drill, and the diameter of the drill hole 1 is not less than 75 mm.

(3) Laying the diameter of the siphon pipe. The siphon with the composite pipe diameter is placed in each drill hole 1, consists of an outer pipe 3 and an inner pipe 4 of a drain pipe, is processed and molded, and ensures that a water inlet of the siphon is positioned at the bottom of the drill hole 1.

(4) The siphon is initiated initially. The water outlet of the siphon is connected with high-pressure water injection equipment, high pressure is generated through manpower or electric power and the like, external water flow is forced to enter the siphon, the siphon reversely flows into a slope body through the siphon, the siphon is filled with water, water injection is stopped, and the water outlet of the siphon is placed under the water surface of the water collecting tank 5 to form initial siphon;

(5) and controlling the underground water level of the side slope. After siphon is started, underground water level in the slope is continuously discharged, when the height difference between the water level in the drill hole 1 and the top point of the siphon is larger than the height of the water column corresponding to the local atmospheric pressure, the siphon process is interrupted, then the water level in the drill hole 1 is caused to rise in the rainfall infiltration process, and when the water level reaches the height above the control water level of the siphon in the drill hole 1, the siphon drainage process is automatically recovered so as to control the water level in the slope to be below a safety line.

Note that: the actual scope of the invention encompasses not only the specific embodiments disclosed above, but also all equivalent ways of practicing or implementing the invention under the claims.

Claims

1. A siphon drainage device for a slope with a composite pipe diameter is characterized by comprising a drainage pipe and water injection equipment; the drain pipe is of a sleeve structure and comprises an external outer drain pipe, and a plurality of inner drain pipes are arranged in the outer drain pipe; and the water outlet of the drain pipe is connected with water injection equipment.

2. The siphon drainage device for slopes with composite pipe diameters as claimed in claim 1, wherein the outer drainage pipe is a drainage pipe with a wall thickness of 3mm and an inner diameter of 17 mm.

3. The siphon drainage device for slopes with composite pipe diameters as claimed in claim 1, wherein the inner drainage pipe is a drainage pipe with a wall thickness of 1.5mm and an inner diameter of 5 mm.

4. The siphon drainage device for slopes with composite pipe diameters as claimed in claim 1, wherein three inner drainage pipes are arranged in the outer drainage pipe.