Soil boring refers to the drilling of the soil for the exploration of soil samples at various depths. Depending on the method in use, the process yields both disturbed and undisturbed soil samples, which undergo examination in line with the set purpose. In this article, you will learn about the methods of soil boring, the soil boring test, a soil boring log, and soil boring vs test pit uses.
Methods of Soil Boring
There are several methods of soil boring available depending on the purpose of the exploration and the resources available for the project. Before choosing a method, the geotechnical engineer should consider the soil type, the desirable type of soil samples, and the availability of the boring technique facility.
This is a popular method of soil boring because it does not require as much equipment as most others. Hence, wash boring provides portability at a low cost. After forming an open hole on the topsoil, the chopping and twisting action of a light bit advances the hole to the desired depth. Then, a water jet passes through rods in the hole to carry out the cutting.
As a result, this method produces disturbed samples which makes it unsuitable for very soft soil, fine to medium grain non-cohesive soil, and cemented soil.
This is another inexpensive and flexible method that serves for both small and large bores. It is a trenchless application where both the casing and helical augers simultaneously drive into the earth surface. The augers remove the excavation, while the casing reduces the likelihood of soil settlement. Because it is a dry method, it is not suitable for very hard soils or cemented soils, and very soft soils, to avoid flow into the hole. But it is ideal for soft to stiff cohesive soils.
When wash and auger boring methods cannot penetrate hard soils or soft rock, percussion drilling provides a strong solution. In this method, drilling occurs by the alternative lifting and dropping of a heavy drill bit via a cable. If penetrating through clay, addition of sand helps the cutting action of the drill bit. For coarse non-cohesive soils, addition of clay increases the carrying capacity of the slurry.
If a soil constitutes highly resistant strata such as rocks, then rotary drilling is the most suitable approach to use. Also, it can serve for other soil types. In this method, a pump circulates water or drilling mud from a pit to remove the soil fragments cut by the drill bit. In addition to removing soil fragments, the drilling fluid helps to stabilize the borehole. Generally, this method is suitable for boring hole diameters of 4 inches (100 mm) and above. Because it becomes uneconomical if used for smaller dimensions than this.
Soil Boring Test
A soil boring test is a technique that investigates and determines the condition and composition of the soil at a site. Moreover, this process involves taking several shallow cores out of the sediment, then carrying out a variety of tests to determine soil characteristics. A soil boring test is site-specific and is due to several reasons.
Purpose of Soil Boring Tests
Construction, mineral exploration, and environmental safety provide three common reasons for conducting soil boring tests on a site:
- Construction: The performance of any structure heavily relies on the design and construction of its foundation. As a result, it is necessary to consider soil-structure interaction at the onset of every construction project. During these tests, the geotechnical engineer determines details of the subsurface soil profile and other static characteristics. Then, this information serves as the basis for designing a foundation suitable for the type of structure that is to be on site.
- Mineral Exploration: Carrying out soil boring tests reveals a lot about the soil composition of a site, including its potential to contain mineral resources. Thus, these tests are integral activities in the exploration of oil and gas, as well as other mineral resources.
- Environmental Safety: Soil boring tests may assess the condition of the soil in such sites in the event of a spillage. In addition, even if there is no spillage, information from these tests enables regulatory bodies to ascertain compliance with industrial waste disposal regulations. Generally, checking soil samples between 0 ft to 3 ft from the surface reveals potential contamination that may affect human, animal, and plant life. Checking depths between 3 ft to 15 ft shows contamination that can affect utility lines.
Soil Boring Log
The soil boring log is the basic record of most geotechnical explorations. Moreover, it contains records that describe exploration procedures and subsurface conditions experienced during drilling, sampling, and coring processes. The basic contents of the log are usually divided into several sections.
The log should contain basic information about the project such as its name/number, location, drilling contractor, drilling equipment, and the boring methods. Additionally, the weather information, personnel carrying out each task, as well as date and time of work should all be covered in detail. Typically, this should be on the first page/sheet of the soil boring log.
Soil Boring Location and Elevation
The exact coordinates of boring, alongside its elevation with respect to a datum, are important information that is always available in a soil boring log. Also, it should contain records of any deviation in the boring location.
Stratigraphy identification summarizes the subsurface conditions on the basis of observation of the soil samples and drill cuttings. Also, comments from the operator about the performance of the drill rig help in describing the strata such as existing fill, topsoil, and pavement sections. The presence and thickness of these strata should be specified. These attributes may have a significant impact on the conclusions and recommendations of geotechnical studies.
The soil boring log should show information about the samples such as sample type, depth, time and date of recovery, and sampler types. Moreover, standard notations, graphical or abbreviations systems should indicate all these details. Also, every sample attempt should have a sequential number for proper identification.
Soil Description and Classification
At a minimum, this section should include soil type, particle distribution, color description, water content condition, and apparent consistency or density. In addition, other details such as inclusions, plasticity, and texture of the soil are necessary to provide an adequate description. All nomenclature, symbols, and categorization should be in line with industry standards such as AASHTO M 145, ASTM D-2487, and ASTM D-2488.
Generally, the presentation of soil boring logs is either horizontal or vertical, as the samples below show.
Soil Boring vs Test Pit
Generally, soil boring and test pits serve similar purposes of uncovering and enabling the investigation of the subsurface conditions at a site. However, there are some differences in their uses as the table below highlights.
Soil Boring Test Pit This is carried out using more complex drilling equipment. Test pits are dug either manually with backhoe equipment or with an excavator. Generally, a more expensive and complex procedure. Because less sophisticated machinery is used, the process incurs less cost. Soil boring is done to varying depths. But, typically deep, in excess of 15 ft. These are shallow, and normally within the range of 3 to 15 ft. The sizes of the holes are limited, allowing for only soil samples to be taken out. The holes are much larger. Thus, allows soil scientists and other professionals to physically examine the soil en masse. Because this accesses greater depths, more complex operations such as monitoring seasonal groundwater levels and exploring mineral resources, can be done. Shallow depths limits operations to carrying out tests for shallow foundation construction and evaluation for soil contamination.
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What is the main advantage of digging a test pit rather than drilling a boring? ›
The biggest benefit of a test pit is cost savings.
Excavators are far less expensive than drilling work, and finding any of the above issues when you're well into a project can cause major time delays and extra expense, pushing out deadlines while costs soar.
There are several boring techniques like auger boring, rotary drilling, wash boring, percussion drilling, auger drilling, and test pits that are employed to collect disturbed and undisturbed samples of soils.What is a soil boring log? ›
The boring log is the basic record of almost every geotechnical exploration and provides a detailed record of the work performed and the findings of the investigation. The field log should be written or printed legibly, and should be kept as clean as is practical.What are the advantages of test pits? ›
The major advantages of test pits over soil borings are as follows: o The near-surface stratigraphy is exposed, facilitating sample collection and recovery and logging of soil, water level, and bedrock surface. o Information is provided on the lateral and vertical extent of subsurface features.What is the difference between borehole and trial pit? ›
Trial pits are more cost effective than boreholes and can enable a greater profile of the soils but are generally restricted to around 3.50m depth with a standard JCB 3CX type machine. The advantages of boreholes is that greater depths can be achieved and more detailed soil and rock strengths can be recorded.What is the most efficient way to dig? ›
- Step 1: String your line and pound the stakes. ...
- Step 2: Carve out a soil divot with a spade. ...
- Step 3: Loosen earth with a tile shovel. ...
- Step 4: Use your clamshell digger. ...
- Step 5: Use a reciprocating saw on large roots. ...
- Step 6: Dislodge rocks with a digging bar. ...
- Step 7: Tamp the soil with the other end.
The different types of boring methods are: Displacement boring. Wash boring. Auger boring.What are the two types of drilling technique for soil? ›
Direct air rotary drilling and reverse air drilling are the most common types. This method penetrates the ground quickly and can penetrate hard formations easily. Air rotary drilling is good for setting monitoring wells at specified layers as well as taking good representative samples of soil at different layers.What are the three bore hole methods employed for soil exploration? ›
- Auger boring. This is simplest method of boring a hole by hand drilling. ...
- Auger and Shell boring. Augers are suitable for soft or stiff clays and very stiff and hard clays and sand pumps for sandy soils. ...
- Wash boring. ...
- Percussion boring. ...
- Rotary boring (Mud rotary drilling)
What Does Test Bore Mean? A test bore is a borehole created for the preliminary investigation of soil conditions at a trenchless construction site. To determine the viability of a project and the tools and methods required, a geotechnical report is produced based on data gathered from the test bore.
What are soil logs used for? ›
Soil log means a detailed description of soil characteristics providing information on the soil's capacity to act as an acceptable treatment and dispersal medium for sewage.Is soil boring test required? ›
Don't start your foundation until a compaction test gives you a positive result. Soil boring test in the Philippines is required for buildings 3 floors and up.What is a test soil boring and why is it performed? ›
A soil boring test is a subsurface investigation of the soil to determine its strength and properties. Soil boring is a technique used to survey soil by taking several shallow cores out of the sediment. The soil can then be tested to be sure it doesn't contain any hazardous contaminants such as oil.What is a test pit in geotechnical engineering? ›
Test pits and test trenches are excavated on site. The test holes are commonly up to 3 m depth and are often dug during the design phase of the project, providing engineers the opportunity to assess the soil and rock conditions to inform on suitable design and construction operations.What are the advantages of testing method? ›
- The testing effect: Retrieval Aids Later Retention. ...
- Testing Identifies Gaps in Knowledge. ...
- Testing Causes Students to Learn More from the Next Study Episode. ...
- Testing Produces Better Organization of Knowledge. ...
- Testing Improves Transfer of Knowledge to New Contexts.
The average depth of a trial hole is anywhere from one metre to 4 metres deep. If you reach a depth of 1.2 metres, you need to bring in structural measures to prevent collapse and to protect people who need to enter the pits. A trial hole or pit is a vital part of any construction project.What is the maximum depth of trial pit? ›
Trial pitting is generally carried out to a maximum depth of 4.5m with standard excavation plant and, depending on soil conditions, is generally suitable for most low rise developments. All trial pit investigations are supervised by experienced engineers with a thorough understanding of geology and soil mechanics.Why is it called a borehole? ›
A borehole is a narrow shaft bored in the ground, either vertically or horizontally.Is it better to dig a hole when the ground is wet or dry? ›
The short answer: typically not. Wetting the soil makes it more complicated to dig up. While it is easier to compact this way, wet soil is far heavier than its dry counterpart. But different types of soil can behave differently, and we will dig into how you can use the moisture of soil to your advantage.Is it better to wet dirt before digging? ›
"We can very quickly lose years of building soil structure if we work the soil when it's too wet," said David Trinklein, horticulture specialist for University of Missouri Extension. COLUMBIA, Mo. — Make sure the soil is ready before you start digging in the garden.
Does wetting soil make it easier to dig? ›
Soil that's turned over when wet will form clods that will be very difficult to break apart later, Trinklein said. This is because wet soil is more easily compacted than dry soil. He recommends the “baseball test” before you start digging.What is the boring test? ›
Test borings are performed to obtain a subsurface profile by allowing for visual classification of soils through sampling. Soil parameters are obtained through various in-situ testing methods which can be used in conjunction with different types of borings.How are soil borings done? ›
Soil boring is a technique used to survey soil by taking several shallow cores out of the sediment. It is done by supporting a drilling jacket or jack-up rig on the soil and drilling into that soil. Conventional soil boring is used to determine the subsurface soil profile and static soil properties.What is the difference between boring and drilling process? ›
Drilling and boring are sometimes confused, but the two processes are used for different purposes. The drilling process creates a hole in the workpiece, while the boring process enlarges a preexisting hole. Boring may be used to create closer tolerances and higher quality finishes in drilled holes.What are the 3 main types of soil testing? ›
You will also see how to test the soil using three of the most common methods: the plasticity test, the thumb penetration test, and the pocket penetrometer test.What are 3 of the most common methods used to test the soil? ›
There are three commonly used methods of testing soilless media using water as an extracting solution: 1:2 dilution method, saturated media extract (SME), and leachate Pour Thru. The values that represent each method of testing are different from each other.What are the two most common types of drilling methods? ›
- Percussion or Cable Drilling.
- Rotary Drilling.
- Dual-Wall Reverse-Circulation Drilling.
- Directional Drilling.
Mud rotary drilling is one of the most common soil and rock drilling types. This method is like air rotary drilling, but in this case, drilling mud is injected via the drill string in order to act as a lubricant to reduce the friction and cool down the drilling bit.What is trial pit excavation? ›
A trial pit (or test pit) is an excavation of ground in order to study or sample the composition and structure of the subsurface, usually dug during a site investigation, a soil survey or a geological survey. Trial pits are dug before the construction.How many types of boreholes are there? ›
Borehole a is an open installation. b, c and d are all closed installation. b is a common U-loop, c is an open system enveloped by a 'sock', d is called coaxial system.
What is the main purpose of digging soil pits as part of making a soil survey? ›
If multiple distinct soil types are present, digging a pit in each can allow for comparison of soil conditions. When examining a soil root pit, the various soil layers (called horizons) should be clearly visible along with the now exposed plant roots (Figure 1).What are the advantages of digging? ›
Digging is important as it breaks up the soil, making it light enough for plants and flowers to grow in. If roots cannot push their way through the soil easily, any plant will be stunted and find it difficult to thrive.What is the main purpose of a boring operation as compared to drilling? ›
Drilling and boring are sometimes confused, but the two processes are used for different purposes. The drilling process creates a hole in the workpiece, while the boring process enlarges a preexisting hole.What is the purpose of pit excavation? ›
excavation of pits allows a simple assessment of the water level and its changes; excavations provide an opportunity to determine the soil and bulk soil layers; it is a proven method of reconstructing roads.What are the two methods of digging? ›
Double digging and trenching:
The depth to which soil is dug depends on the requirement of the plant.
Soil log means a detailed description of soil characteristics providing information on the soil's capacity to act as an acceptable treatment and dispersal medium for sewage.How are test pits done? ›
Test Pits will be excavated with backhoe equipment to provide detailed visual examination of near surface soil, groundwater, and bedrock conditions. Test Pit soil samples may be collected using stainless steel and/or Teflon-lined scoops, trowels, shovels, spoons, or spatulas.Why is no-dig better? ›
Digging your garden can break up the fungal threads in the soil, meaning that your plants don't benefit from these helpful organisms. No-dig gardening allows natural relationships between organisms to flourish and preserves the overall structure of the soil, leading to improved plant growth.Why do we double dig? ›
Double digging is a useful way of cultivating soil in new gardens and in situations where deep topsoil is required. Ordinary digging is good enough for most circumstances.Why is no-dig gardening good? ›
The idea behind no-dig gardening is to mimic a natural ecosystem by allowing the soil to develop its natural structure, life and vitality. As a result, the plants grow better, there is less work to do, and fewer disease and insect problems arise.
Why a boring tool Cannot be used for drilling? ›
Boring is a metal cutting operation to enlarge existing hole diameter by using a single point edge cutting tool. This process is different from drilling operations because boring requires an existing hole.Which operation is first performed drilling or boring? ›
It must be drilling first. Drilling is originating a hole and boring is enlarging the hole previously drilled in drilling.What are the 3 types of excavation? ›
Cut and fill: This excavation method strips layers from the earth and can include grading. Muck: Muck excavation removes mud, water and dirt, often moving it elsewhere to allow it to dry. Drainage: This type works to divert water, and can include trenches and canals.What is the difference between trench and pit excavation? ›
A pit was defined as a single excavation, circular in appearance, with well-defined edges, and where the ratio between the length and the width of the excavation did not exceed two. A trench was defined as an elongated and continuous excavation, with well-defined edges and at least two times longer than its width.