Construction of Open Wells

如何建造水井？

水井不仅仅是一个钻孔，但是对于许多人来说，钻井过程的上方部分是他们看到的唯一部分。水井是地面上特殊设计的孔。

For ground water monitoring, or for scientific research purposes, wells may be drilled in a way that allows the specialists to closely examine the rock formations and take frequent water samples.

高级井和钻石核心钻探是经常用于科学目的的钻井技术。

Most home wells are drilled to 8 or 6 inches in diameter. Municipal or irrigation wells are likely to be drilled at larger diameters, sometimes as much as 24 inches or more.

Types of well drilling methods

Three methods typically used for drilling water wells are rotary, air hammer and cable tool

1. Rotary Method of drilling wells
2. Air Hammer Method
3. Cable tool Method

1. Rotary:

In rotary drilling, a drill bit is attached to a length of connected drill pipe. The drill bit will be made of tough metals such as tungsten, and as the drill is rotated, the bit acts to grind up the rock. The broken pieces (cuttings) are flushed upward and out of the hole by circulating a drilling fluid (sometime called drilling mud) down through the drill pipe and back to the surface.

这drilling fluid also serves to cool and lubricate the drill bit, and by stabilizing the wall of the hole, it can prevent possible cavein of unstable sands or crumbly rock before the well casing or well screen is installed. As the drill intersects water bearing rock formations water will flow into the hole. Most drillers carefully monitor the depth of water "strikes" and keep a note of the formations in which they occur.

2. Air Hammer:

3.电缆工具方法：

See also:Video of Cable Tool Method

另一种钻井技术使用“磅”机器，通常称为电缆工具钻孔。使用这种方法，将钻头固定在电缆的末端，并反复抬起并掉落，向下撞击。定期将插条从孔中救出。该方法很慢，在大多数地方都被旋转钻孔所取代。但是，电缆工具方法负责全球数百万个成功的井。

类型1

Well with impervious lining

Resting on impervious layer

1. 坑是挖掘的
2. Masonry lining is built up on a kerb upto few meters above ground level
3. 路缘 - 戒指（R.C.C）在底部具有尖端
4. Kerb is descended by loading sand bags
   1. 砌体下沉，进一步建造在顶部
   2. Vertical alignment is done through plumbob
   3. When w.t is reached, further sinking is done by pumping water
   4. A JHAM self closing bucket which is operated by pulley and rope
   5. The soil is retained and water oozes out
   6. The sinking continues till impervious layer is reached.
   7. Then bore hole (small dia) is made through impervious layer which is protected by timber lining

类型2

Wells with pervious lining such as brick stone and fed through pores

Sides are lined with bricks or stones without mortar

• 水通过侧面进入
• Ffor stability concrete plug (1m depth) is installed
• Pervious lining is surrounded by gravel filter

类型3

No lining at all in kacha wells or unlined wells

• Temporary wells in hard soils
• When water table is high (4m high)
• Cheap and useful but collapse

离心泵的横截面井

排放开放式井3-6 L/sec

Discharge of tube well 40-45 l/sec

• Tube well is an assembly of pipes and strainers
• It is bored deep into ground intercepting one or more bearing strata (aquifers)
• A centrifugal pump is connected to main pipe of tube well

Considerations \ Precautions in drilling wells

1. 需要强大的技能来指导和控制水井钻头，因为它穿透了地下深处的沙子，砾石，粘土和固体岩层。

2. The drill rods can weigh several tons; if the drill pushes too hard or turns too fast, the drill bit will wear out; if it does not push hard enough, it won't penetrate the rocks.

3. There are often several rock layers in a single well; each may need different drilling pressures. Once water is encountered, the driller will need to keep a close watch on the drilling process.

4. 无论使用哪种钻孔方法，井的顶部通常都衬有钢制或塑料井外壳。

5. The diameter of the drilled hole is usually an inch or two wider than the diameter of the casing.

6. The space between the drilled hole and the casing (the annulus) has to be filled to prevent the chance of polluted surface water from migrating downward along the outside of the casing where it might contaminate the aquifer. This filling is called "grout"