Evaluating Soil Moisture Fluctuations Beneath Homes

Evaluating Soil Moisture Fluctuations Beneath Homes

Examination of the methods used to identify expansive clay in a property

Overview of common causes for soil moisture fluctuations around homes


Soil moisture fluctuations around homes are a common issue that can lead to various problems, including foundation settlement, basement flooding, and landscaping issues. Foundation drainage solutions help prevent water-related damage foundation crack repair service building insulation. Understanding the causes behind these fluctuations is crucial for homeowners and property managers to mitigate potential damage and maintain a stable environment. Here, we explore some of the most common causes for soil moisture fluctuations beneath homes.

One primary cause of soil moisture fluctuation is natural weather patterns. Rainfall, snowfall, and changes in temperature can significantly impact soil moisture levels. During periods of heavy rain, soil can become saturated, leading to increased moisture content. Conversely, during dry spells, soil moisture can decrease, causing the soil to shrink and potentially leading to foundation issues.

Another significant factor is irrigation practices. Many homeowners use irrigation systems to maintain their lawns and gardens. While these systems are beneficial for plant growth, they can also contribute to soil moisture fluctuations. Over-irrigation can lead to excessive moisture, while under-irrigation can result in dry soil conditions. It's essential to balance irrigation to avoid extreme moisture levels.

Landscaping and grading around a home also play a crucial role in soil moisture fluctuations. Improper grading can cause water to pool around the foundation, leading to increased soil moisture. On the other hand, well-graded landscapes direct water away from the home, helping to maintain more stable soil moisture levels. Additionally, the type of vegetation planted can affect soil moisture; deep-rooted plants can help stabilize soil, while shallow-rooted plants may exacerbate moisture fluctuations.

Seasonal changes and the presence of nearby water bodies can also influence soil moisture levels. In colder climates, the freeze-thaw cycle can cause soil expansion and contraction, leading to moisture fluctuations. Homes near rivers, lakes, or groundwater sources may experience higher soil moisture levels due to the proximity of these water bodies.

Lastly, human activities such as construction and landscaping projects can disrupt natural soil conditions, leading to moisture fluctuations. Excavation and grading during construction can alter the soil's natural drainage patterns, while landscaping projects may introduce new plants and irrigation systems that affect soil moisture.

In conclusion, soil moisture fluctuations around homes are influenced by a variety of factors, including natural weather patterns, irrigation practices, landscaping and grading, seasonal changes, nearby water bodies, and human activities. By understanding these causes, homeowners and property managers can take proactive steps to manage soil moisture levels and prevent potential issues related to foundation stability and landscaping health.

Methods for evaluating soil moisture levels beneath residential properties


Evaluating soil moisture levels beneath residential properties is crucial for understanding the stability of the soil and the integrity of the foundation of homes. Various methods exist to assess these moisture levels, each with its own advantages and limitations. Here are some commonly used methods:

1. **Soil Sampling and Laboratory Analysis**:
This method involves taking soil samples from different depths beneath the property. These samples are then sent to a laboratory where they undergo various tests to determine moisture content, soil type, and other relevant properties. While this method is accurate, it can be time-consuming and costly.

2. **Moisture Meters**:
Moisture meters provide a quick and non-destructive way to measure soil moisture. These devices work by inserting probes into the soil, which then measure the electrical resistance or capacitance. Lower resistance or higher capacitance typically indicates higher moisture levels. This method is handy for quick assessments but may not provide detailed information about soil properties.

3. **Time Domain Reflectometry (TDR)**:
TDR is a more advanced technique that involves sending electromagnetic pulses through the soil and measuring the time it takes for the pulse to return. The speed of the pulse is affected by the soil's dielectric properties, which change with moisture content. TDR provides accurate measurements but requires specialized equipment and training.

4. **Ground-Penetrating Radar (GPR)**:
GPR uses high-frequency radio waves to create a subsurface image of the soil. By analyzing the reflected waves, one can infer moisture levels and other soil characteristics. GPR is non-invasive and can cover large areas quickly, but interpreting the data requires expertise.

5. **Remote Sensing**:
Satellite imagery and aerial photography can be used to monitor soil moisture over large areas. These methods rely on detecting surface moisture and inferring subsurface conditions. While useful for broad-scale assessments, they may not provide the detailed information needed for individual properties.

6. **Lysimeters**:
Lysimeters are devices that measure water movement through soil. They consist of a container filled with soil, placed in the ground, and equipped with sensors to monitor water content. This method provides continuous data but is limited to the specific location of the lysimeter.

Each of these methods has its own set of advantages and limitations. The choice of method depends on factors such as the need for accuracy, the scale of assessment, budget constraints, and the specific conditions of the property. By employing these methods, homeowners and professionals can better understand soil moisture fluctuations and take appropriate measures to maintain the stability and safety of residential properties.

Impact of soil moisture changes on different types of residential foundations


Soil moisture is a critical factor in the stability and longevity of residential foundations. Understanding its impact is essential for homeowners, builders, and engineers alike. Let's explore how changes in soil moisture affect different types of residential foundations: slab-on-grade, crawl space, and basement foundations.

Slab-on-grade foundations, which are common in warmer climates, are directly poured onto the ground. They are particularly sensitive to soil moisture changes. When soil becomes overly saturated, it can lead to a phenomenon known as heave, where the soil expands and pushes upward on the foundation. Conversely, during dry periods, the soil can shrink, causing the foundation to settle unevenly. This can result in cracks in the foundation and, ultimately, structural issues within the home.

Crawl space foundations elevate the home above the ground, providing a space beneath for ventilation and storage. Changes in soil moisture can significantly impact these foundations. Excessive moisture can lead to mold growth, wood rot, and pest infestations. Additionally, if the soil beneath the crawl space becomes too moist, it can lose its bearing capacity, causing the foundation to settle. On the other hand, during dry spells, the soil can shrink, leading to sagging floors and potential structural damage.

Basement foundations are the most complex and are typically found in areas with colder climates. These foundations are below ground level and are surrounded by soil on all sides. Fluctuations in soil moisture can have severe consequences for basement foundations. High moisture levels can lead to water infiltration, causing dampness, mold, and even flooding. Prolonged exposure to moisture can weaken the foundation walls, leading to bowing or cracking. During dry periods, the soil can shrink, pulling away from the foundation walls and causing them to crack under the pressure.

In conclusion, soil moisture changes have a profound impact on different types of residential foundations. Homeowners must be vigilant about monitoring soil moisture levels and taking appropriate measures to mitigate potential issues. Regular inspections, proper drainage systems, and moisture barriers can help protect foundations from the adverse effects of soil moisture fluctuations, ensuring the stability and longevity of homes.

Case studies showcasing effects of soil moisture on home foundations


When it comes to evaluating the effects of soil moisture on home foundations, case studies provide invaluable insights. These real-life examples demonstrate how fluctuations in soil moisture levels can lead to significant structural issues for homes.

One notable case study involves a suburban home in a region prone to heavy rainfall. Over several years, the homeowners noticed cracks forming in their foundation and walls. Upon investigation, soil tests revealed that the clay-rich soil around the house expanded significantly when wet, exerting pressure on the foundation. This phenomenon, known as heave, caused the foundation to lift unevenly, leading to the observed cracks. The solution involved installing a proper drainage system to manage rainwater and reduce soil moisture levels around the foundation.

Another compelling case is from a coastal area where homes are built on sandy soil. Here, the primary concern was not so much the expansion of soil but its erosion due to fluctuating moisture levels. During periods of high tide or heavy rain, the water table rose, saturating the soil and reducing its load-bearing capacity. This led to settling and sinking of the home's foundation. The case study highlighted the importance of using pilings driven deep into more stable soil layers to support the home, effectively mitigating the effects of soil moisture fluctuations.

In a third example, a home in a semi-arid region faced issues due to the opposite problem-desiccation of the soil. During prolonged dry spells, the soil shrank, creating voids beneath the foundation. This resulted in uneven settling and significant structural cracks. The solution involved regular monitoring of soil moisture levels and the implementation of irrigation systems to maintain consistent soil moisture, preventing extreme desiccation.

These case studies underscore the critical need for homeowners and builders to understand and manage soil moisture levels. By learning from these examples, we can better protect homes from the detrimental effects of soil moisture fluctuations, ensuring structural integrity and longevity.

Preventive measures homeowners can take to mitigate soil moisture issues


Certainly! Here's a human-like essay on preventive measures homeowners can take to mitigate soil moisture issues:

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When it comes to maintaining the integrity of our homes, one often overlooked yet crucial factor is soil moisture. Fluctuations in soil moisture can lead to a host of problems, from foundation cracks to mold growth. Fortunately, there are several preventive measures homeowners can take to mitigate these issues and ensure a stable, healthy living environment.

First and foremost, proper landscaping is key. Ensuring that your yard is graded away from your home helps to direct water flow away from the foundation. This simple adjustment can significantly reduce the amount of moisture that accumulates around your home. Additionally, installing French drains can further assist in diverting water away from the foundation, providing an effective solution for managing excess moisture.

Another important step is to maintain your gutters and downspouts. Clogged gutters can cause water to overflow and seep into the soil around your home, leading to increased moisture levels. Regularly cleaning gutters and ensuring that downspouts extend at least four to six feet away from the house can help prevent this issue.

Incorporating permeable materials in your landscaping can also make a big difference. Using gravel, mulch, or other permeable ground covers allows water to infiltrate the soil more gradually, reducing the risk of soil saturation. This not only helps manage moisture levels but also promotes healthier plant growth.

Homeowners should also consider the use of a vapor barrier in their basements or crawl spaces. A vapor barrier is a material that resists the passage of water vapor, helping to keep moisture levels in check. This is particularly important in areas prone to high humidity or frequent rainfall.

Lastly, regular inspections of your home's exterior can help identify potential moisture issues before they become serious problems. Look for signs of water pooling near the foundation, cracks in the walls, or musty odors, and address these issues promptly.

By taking these preventive measures, homeowners can effectively mitigate soil moisture issues, protecting their homes from potential damage and ensuring a safer, more stable living environment.

Professional services available for addressing soil moisture-related foundation problems


Certainly!

When it comes to evaluating soil moisture fluctuations beneath homes, it's essential to understand the role of professional services in addressing potential foundation problems. Soil moisture can have a profound impact on the stability of a home's foundation. When the soil around a foundation becomes too wet or too dry, it can lead to issues such as foundation cracking, sinking, or shifting. These problems can be both costly and dangerous if not addressed promptly.

Professional services specializing in soil moisture-related foundation problems offer a range of solutions tailored to the specific needs of each home. These experts start by conducting a thorough assessment of the soil conditions around the foundation. They use advanced equipment and techniques to measure soil moisture levels, identify areas of concern, and determine the root causes of any fluctuations.

Once the assessment is complete, these professionals provide detailed recommendations for remediation. This might include installing drainage systems to redirect water away from the foundation, using moisture barriers to prevent water from seeping into the soil, or implementing aeration techniques to improve soil structure and drainage. In some cases, they may also suggest the use of chemical stabilizers to bind soil particles together, reducing the impact of moisture fluctuations.

Moreover, professional services don't just stop at remediation. They also offer ongoing monitoring and maintenance plans to ensure that soil moisture levels remain stable over time. This proactive approach helps prevent future foundation issues, saving homeowners both time and money in the long run.

In conclusion, when dealing with soil moisture-related foundation problems, seeking the expertise of professional services is crucial. Their knowledge, experience, and specialized tools enable them to accurately assess, remediate, and monitor soil conditions, ensuring the long-term stability and safety of your home's foundation.



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Residential Foundation Repair Services

Strong Foundations, Strong Homes


A mobile home being repaired in Oklahoma
A person making these repairs to a house after a flood

Home repair involves the diagnosis and resolution of problems in a home, and is related to home maintenance to avoid such problems. Many types of repairs are "do it yourself" (DIY) projects, while others may be so complicated, time-consuming or risky as to require the assistance of a qualified handyperson, property manager, contractor/builder, or other professionals.

Home repair is not the same as renovation, although many improvements can result from repairs or maintenance. Often the costs of larger repairs will justify the alternative of investment in full-scale improvements. It may make just as much sense to upgrade a home system (with an improved one) as to repair it or incur ever-more-frequent and expensive maintenance for an inefficient, obsolete or dying system.

Worn, consumed, dull, dirty, clogged

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Repairs often mean simple replacement of worn or used components intended to be periodically renewed by a home-owner, such as burnt out light bulbs, worn out batteries, or overfilled vacuum cleaner bags. Another class of home repairs relates to restoring something to a useful condition, such as sharpening tools or utensils, replacing leaky faucet washers, cleaning out plumbing traps, rain gutters. Because of the required precision, specialized tools, or hazards, some of these are best left to experts such as a plumber. One emergency repair that may be necessary in this area is overflowing toilets. Most of them have a shut-off valve on a pipe beneath or behind them so that the water supply can be turned off while repairs are made, either by removing a clog or repairing a broken mechanism.

Broken or damaged

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Perhaps the most perplexing repairs facing a home-owner are broken or damaged things. In today's era of built-in obsolescence for many products, it is often more convenient to replace something rather than attempt to repair it. A repair person is faced with the tasks of accurately identifying the problem, then finding the materials, supplies, tools and skills necessary to sufficiently effect the repair. Some things, such as broken windows, appliances or furniture can be carried to a repair shop, but there are many repairs that can be performed easily enough, such as patching holes in plaster and drywall, cleaning stains, repairing cracked windows and their screens, or replacing a broken electrical switch or outlet. Other repairs may have some urgency, such as broken water pipes, broken doors, latches or windows, or a leaky roof or water tank, and this factor can certainly justify calling for professional help. A home handyperson may become adept at dealing with such immediate repairs, to avoid further damage or loss, until a professional can be summoned.

Emergency repairs

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Emergencies can happen at any time, so it is important to know how to quickly and efficiently fix the problem. From natural disasters, power loss, appliance failure and no water, emergency repairs tend to be one of the most important repairs to be comfortable and confident with. In most cases, the repairs are DIY or fixable with whatever is around the house. Common repairs would be fixing a leak, broken window, flooding, frozen pipes or clogged toilet. Each problem can have a relatively simple fix, a leaky roof and broken window can be patched, a flood can be pumped out, pipes can be thawed and repaired and toilets can be unclogged with a chemical. For the most part, emergency repairs are not permanent. They are what you can do fast to stop the problem then have a professional come in to permanently fix it.[1] Flooding as a result of frozen pipes, clogged toilets or a leaky roof can result in very costly water damage repairs and even potential health issues resulting from mold growth if not addressed in a timely manner.

Maintenance

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Periodic maintenance also falls under the general class of home repairs. These are inspections, adjustments, cleaning, or replacements that should be done regularly to ensure proper functioning of all the systems in a house, and to avoid costly emergencies. Examples include annual testing and adjustment of alarm systems, central heating or cooling systems (electrodes, thermocouples, and fuel filters), replacement of water treatment components or air-handling filters, purging of heating radiators and water tanks, defrosting a freezer, vacuum refrigerator coils, refilling dry floor-drain traps with water, cleaning out rain gutters, down spouts and drains, touching up worn house paint and weather seals, and cleaning accumulated creosote out of chimney flues, which may be best left to a chimney sweep.

Examples of less frequent home maintenance that should be regularly forecast and budgeted include repainting or staining outdoor wood or metal, repainting masonry, waterproofing masonry, cleaning out septic systems, replacing sacrificial electrodes in water heaters, replacing old washing machine hoses (preferably with stainless steel hoses less likely to burst and cause a flood), and other home improvements such as replacement of obsolete or ageing systems with limited useful lifetimes (water heaters, wood stoves, pumps, and asphaltic or wooden roof shingles and siding.

Often on the bottom of people's to-do list is home maintenance chores, such as landscaping, window and gutter cleaning, power washing the siding and hard-scape, etc. However, these maintenance chores pay for themselves over time. Often, injury could occur when operating heavy machinery or when climbing on ladders or roofs around your home, so if an individual is not in the proper physical condition to accomplish these chores, then they should consult a professional. Lack of maintenance will cost more due to higher costs associated with repairs or replacements to be made later. It requires discipline and learning aptitude to repair and maintain the home in good condition, but it is a satisfying experience to perform even seemingly minor repairs.

Good operations

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Another related issue for avoiding costly repairs (or disasters) is the proper operation of a home, including systems and appliances, in a way that prevents damage or prolongs their usefulness. For example, at higher latitudes, even a clean rain gutter can suddenly build up an ice dam in winter, forcing melt water into unprotected roofing, resulting in leaks or even flooding inside walls or rooms. This can be prevented by installing moisture barrier beneath the roofing tiles. A wary home-owner should be alert to the conditions that can result in larger problems and take remedial action before damage or injury occurs. It may be easier to tack down a bit of worn carpet than repair a large patch damaged by prolonged misuse. Another example is to seek out the source of unusual noises or smells when mechanical, electrical or plumbing systems are operating—sometimes they indicate incipient problems. One should avoid overloading or otherwise misusing systems, and a recurring overload may indicate time for an upgrade.

Water infiltration is one of the most insidious sources of home damage. Small leaks can lead to water stains, and rotting wood. Soft, rotten wood is an inviting target for termites and other wood-damaging insects. Left unattended, a small leak can lead to significant structural damage, necessitating the replacement of beams and framing.

With a useful selection of tools, typical materials and supplies on hand, and some home repair information or experience, a home-owner or handyperson should be able to carry out a large number of DIY home repairs and identify those that will need the specialized attention of others.

Remediation of environmental problems

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When a home is sold, inspections are performed that may reveal environmental hazards such as radon gas in the basement or water supply or friable asbestos materials (both of which can cause lung cancer), peeling or disturbed lead paint (a risk to children and pregnant women), in-ground heating oil tanks that may contaminate ground water, or mold that can cause problems for those with asthma or allergies. Typically the buyer or mortgage lender will require these conditions to be repaired before allowing the purchase to close. An entire industry of environmental remediation contractors has developed to help home owners resolve these types of problems.

See also

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  • Electrical wiring
  • Handyperson
  • Housekeeping
  • Home improvement
  • Home wiring
  • HVAC
  • Maintenance, repair, and operations
  • Plumbing
  • Right to repair
  • Smoke alarm
  • Winterization

References

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  1. ^ Reader's Digest New Complete Do-it-yourself Manual. Montreal, Canada: Reader's Digest Association. 1991. pp. 9–13. ISBN 9780888501783. OCLC 1008853527.

 

 

Boston's Big Dig presented geotechnical challenges in an urban environment.
Precast concrete retaining wall
A typical cross-section of a slope used in two-dimensional analyzes.

Geotechnical engineering, also known as geotechnics, is the branch of civil engineering concerned with the engineering behavior of earth materials. It uses the principles of soil mechanics and rock mechanics to solve its engineering problems. It also relies on knowledge of geology, hydrology, geophysics, and other related sciences.

Geotechnical engineering has applications in military engineering, mining engineering, petroleum engineering, coastal engineering, and offshore construction. The fields of geotechnical engineering and engineering geology have overlapping knowledge areas. However, while geotechnical engineering is a specialty of civil engineering, engineering geology is a specialty of geology.

History

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Humans have historically used soil as a material for flood control, irrigation purposes, burial sites, building foundations, and construction materials for buildings. Dykes, dams, and canals dating back to at least 2000 BCE—found in parts of ancient Egypt, ancient Mesopotamia, the Fertile Crescent, and the early settlements of Mohenjo Daro and Harappa in the Indus valley—provide evidence for early activities linked to irrigation and flood control. As cities expanded, structures were erected and supported by formalized foundations. The ancient Greeks notably constructed pad footings and strip-and-raft foundations. Until the 18th century, however, no theoretical basis for soil design had been developed, and the discipline was more of an art than a science, relying on experience.[1]

Several foundation-related engineering problems, such as the Leaning Tower of Pisa, prompted scientists to begin taking a more scientific-based approach to examining the subsurface. The earliest advances occurred in the development of earth pressure theories for the construction of retaining walls. Henri Gautier, a French royal engineer, recognized the "natural slope" of different soils in 1717, an idea later known as the soil's angle of repose. Around the same time, a rudimentary soil classification system was also developed based on a material's unit weight, which is no longer considered a good indication of soil type.[1][2]

The application of the principles of mechanics to soils was documented as early as 1773 when Charles Coulomb, a physicist and engineer, developed improved methods to determine the earth pressures against military ramparts. Coulomb observed that, at failure, a distinct slip plane would form behind a sliding retaining wall and suggested that the maximum shear stress on the slip plane, for design purposes, was the sum of the soil cohesion, , and friction , where is the normal stress on the slip plane and is the friction angle of the soil. By combining Coulomb's theory with Christian Otto Mohr's 2D stress state, the theory became known as Mohr-Coulomb theory. Although it is now recognized that precise determination of cohesion is impossible because is not a fundamental soil property, the Mohr-Coulomb theory is still used in practice today.[3]

In the 19th century, Henry Darcy developed what is now known as Darcy's Law, describing the flow of fluids in a porous media. Joseph Boussinesq, a mathematician and physicist, developed theories of stress distribution in elastic solids that proved useful for estimating stresses at depth in the ground. William Rankine, an engineer and physicist, developed an alternative to Coulomb's earth pressure theory. Albert Atterberg developed the clay consistency indices that are still used today for soil classification.[1][2] In 1885, Osborne Reynolds recognized that shearing causes volumetric dilation of dense materials and contraction of loose granular materials.

Modern geotechnical engineering is said to have begun in 1925 with the publication of Erdbaumechanik by Karl von Terzaghi, a mechanical engineer and geologist. Considered by many to be the father of modern soil mechanics and geotechnical engineering, Terzaghi developed the principle of effective stress, and demonstrated that the shear strength of soil is controlled by effective stress.[4] Terzaghi also developed the framework for theories of bearing capacity of foundations, and the theory for prediction of the rate of settlement of clay layers due to consolidation.[1][3][5] Afterwards, Maurice Biot fully developed the three-dimensional soil consolidation theory, extending the one-dimensional model previously developed by Terzaghi to more general hypotheses and introducing the set of basic equations of Poroelasticity.

In his 1948 book, Donald Taylor recognized that the interlocking and dilation of densely packed particles contributed to the peak strength of the soil. Roscoe, Schofield, and Wroth, with the publication of On the Yielding of Soils in 1958, established the interrelationships between the volume change behavior (dilation, contraction, and consolidation) and shearing behavior with the theory of plasticity using critical state soil mechanics. Critical state soil mechanics is the basis for many contemporary advanced constitutive models describing the behavior of soil.[6]

In 1960, Alec Skempton carried out an extensive review of the available formulations and experimental data in the literature about the effective stress validity in soil, concrete, and rock in order to reject some of these expressions, as well as clarify what expressions were appropriate according to several working hypotheses, such as stress-strain or strength behavior, saturated or non-saturated media, and rock, concrete or soil behavior.

Roles

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Geotechnical investigation

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Geotechnical engineers investigate and determine the properties of subsurface conditions and materials. They also design corresponding earthworks and retaining structures, tunnels, and structure foundations, and may supervise and evaluate sites, which may further involve site monitoring as well as the risk assessment and mitigation of natural hazards.[7][8]

Geotechnical engineers and engineering geologists perform geotechnical investigations to obtain information on the physical properties of soil and rock underlying and adjacent to a site to design earthworks and foundations for proposed structures and for the repair of distress to earthworks and structures caused by subsurface conditions. Geotechnical investigations involve surface and subsurface exploration of a site, often including subsurface sampling and laboratory testing of retrieved soil samples. Sometimes, geophysical methods are also used to obtain data, which include measurement of seismic waves (pressure, shear, and Rayleigh waves), surface-wave methods and downhole methods, and electromagnetic surveys (magnetometer, resistivity, and ground-penetrating radar). Electrical tomography can be used to survey soil and rock properties and existing underground infrastructure in construction projects.[9]

Surface exploration can include on-foot surveys, geologic mapping, geophysical methods, and photogrammetry. Geologic mapping and interpretation of geomorphology are typically completed in consultation with a geologist or engineering geologist. Subsurface exploration usually involves in-situ testing (for example, the standard penetration test and cone penetration test). The digging of test pits and trenching (particularly for locating faults and slide planes) may also be used to learn about soil conditions at depth. Large-diameter borings are rarely used due to safety concerns and expense. Still, they are sometimes used to allow a geologist or engineer to be lowered into the borehole for direct visual and manual examination of the soil and rock stratigraphy.

Various soil samplers exist to meet the needs of different engineering projects. The standard penetration test, which uses a thick-walled split spoon sampler, is the most common way to collect disturbed samples. Piston samplers, employing a thin-walled tube, are most commonly used to collect less disturbed samples. More advanced methods, such as the Sherbrooke block sampler, are superior but expensive. Coring frozen ground provides high-quality undisturbed samples from ground conditions, such as fill, sand, moraine, and rock fracture zones.[10]

Geotechnical centrifuge modeling is another method of testing physical-scale models of geotechnical problems. The use of a centrifuge enhances the similarity of the scale model tests involving soil because soil's strength and stiffness are susceptible to the confining pressure. The centrifugal acceleration allows a researcher to obtain large (prototype-scale) stresses in small physical models.

Foundation design

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The foundation of a structure's infrastructure transmits loads from the structure to the earth. Geotechnical engineers design foundations based on the load characteristics of the structure and the properties of the soils and bedrock at the site. Generally, geotechnical engineers first estimate the magnitude and location of loads to be supported before developing an investigation plan to explore the subsurface and determine the necessary soil parameters through field and lab testing. Following this, they may begin the design of an engineering foundation. The primary considerations for a geotechnical engineer in foundation design are bearing capacity, settlement, and ground movement beneath the foundations.[11]

Earthworks

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A compactor/roller operated by U.S. Navy Seabees

Geotechnical engineers are also involved in the planning and execution of earthworks, which include ground improvement,[11] slope stabilization, and slope stability analysis.

Ground improvement

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Various geotechnical engineering methods can be used for ground improvement, including reinforcement geosynthetics such as geocells and geogrids, which disperse loads over a larger area, increasing the soil's load-bearing capacity. Through these methods, geotechnical engineers can reduce direct and long-term costs.[12]

Slope stabilization

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Simple slope slip section.

Geotechnical engineers can analyze and improve slope stability using engineering methods. Slope stability is determined by the balance of shear stress and shear strength. A previously stable slope may be initially affected by various factors, making it unstable. Nonetheless, geotechnical engineers can design and implement engineered slopes to increase stability.

Slope stability analysis
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Stability analysis is needed to design engineered slopes and estimate the risk of slope failure in natural or designed slopes by determining the conditions under which the topmost mass of soil will slip relative to the base of soil and lead to slope failure.[13] If the interface between the mass and the base of a slope has a complex geometry, slope stability analysis is difficult and numerical solution methods are required. Typically, the interface's exact geometry is unknown, and a simplified interface geometry is assumed. Finite slopes require three-dimensional models to be analyzed, so most slopes are analyzed assuming that they are infinitely wide and can be represented by two-dimensional models.

Sub-disciplines

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Geosynthetics

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A collage of geosynthetic products.

Geosynthetics are a type of plastic polymer products used in geotechnical engineering that improve engineering performance while reducing costs. This includes geotextiles, geogrids, geomembranes, geocells, and geocomposites. The synthetic nature of the products make them suitable for use in the ground where high levels of durability are required. Their main functions include drainage, filtration, reinforcement, separation, and containment.

Geosynthetics are available in a wide range of forms and materials, each to suit a slightly different end-use, although they are frequently used together. Some reinforcement geosynthetics, such as geogrids and more recently, cellular confinement systems, have shown to improve bearing capacity, modulus factors and soil stiffness and strength.[14] These products have a wide range of applications and are currently used in many civil and geotechnical engineering applications including roads, airfields, railroads, embankments, piled embankments, retaining structures, reservoirs, canals, dams, landfills, bank protection and coastal engineering.[15]

Offshore

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Platforms offshore Mexico.

Offshore (or marine) geotechnical engineering is concerned with foundation design for human-made structures in the sea, away from the coastline (in opposition to onshore or nearshore engineering). Oil platforms, artificial islands and submarine pipelines are examples of such structures.[16]

There are a number of significant differences between onshore and offshore geotechnical engineering.[16][17] Notably, site investigation and ground improvement on the seabed are more expensive; the offshore structures are exposed to a wider range of geohazards; and the environmental and financial consequences are higher in case of failure. Offshore structures are exposed to various environmental loads, notably wind, waves and currents. These phenomena may affect the integrity or the serviceability of the structure and its foundation during its operational lifespan and need to be taken into account in offshore design.

In subsea geotechnical engineering, seabed materials are considered a two-phase material composed of rock or mineral particles and water.[18][19] Structures may be fixed in place in the seabed—as is the case for piers, jetties and fixed-bottom wind turbines—or may comprise a floating structure that remains roughly fixed relative to its geotechnical anchor point. Undersea mooring of human-engineered floating structures include a large number of offshore oil and gas platforms and, since 2008, a few floating wind turbines. Two common types of engineered design for anchoring floating structures include tension-leg and catenary loose mooring systems.[20]

Observational method

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First proposed by Karl Terzaghi and later discussed in a paper by Ralph B. Peck, the observational method is a managed process of construction control, monitoring, and review, which enables modifications to be incorporated during and after construction. The method aims to achieve a greater overall economy without compromising safety by creating designs based on the most probable conditions rather than the most unfavorable.[21] Using the observational method, gaps in available information are filled by measurements and investigation, which aid in assessing the behavior of the structure during construction, which in turn can be modified per the findings. The method was described by Peck as "learn-as-you-go".[22]

The observational method may be described as follows:[22]

  1. General exploration sufficient to establish the rough nature, pattern, and properties of deposits.
  2. Assessment of the most probable conditions and the most unfavorable conceivable deviations.
  3. Creating the design based on a working hypothesis of behavior anticipated under the most probable conditions.
  4. Selection of quantities to be observed as construction proceeds and calculating their anticipated values based on the working hypothesis under the most unfavorable conditions.
  5. Selection, in advance, of a course of action or design modification for every foreseeable significant deviation of the observational findings from those predicted.
  6. Measurement of quantities and evaluation of actual conditions.
  7. Design modification per actual conditions

The observational method is suitable for construction that has already begun when an unexpected development occurs or when a failure or accident looms or has already happened. It is unsuitable for projects whose design cannot be altered during construction.[22]

See also

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  • Civil engineering
  • Deep Foundations Institute
  • Earthquake engineering
  • Earth structure
  • Effective stress
  • Engineering geology
  • Geological Engineering
  • Geoprofessions
  • Hydrogeology
  • International Society for Soil Mechanics and Geotechnical Engineering
  • Karl von Terzaghi
  • Land reclamation
  • Landfill
  • Mechanically stabilized earth
  • Offshore geotechnical engineering
  • Rock mass classifications
  • Sediment control
  • Seismology
  • Soil mechanics
  • Soil physics
  • Soil science

 

Notes

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  1. ^ a b c d Das, Braja (2006). Principles of Geotechnical Engineering. Thomson Learning.
  2. ^ a b Budhu, Muni (2007). Soil Mechanics and Foundations. John Wiley & Sons, Inc. ISBN 978-0-471-43117-6.
  3. ^ a b Disturbed soil properties and geotechnical design, Schofield, Andrew N., Thomas Telford, 2006. ISBN 0-7277-2982-9
  4. ^ Guerriero V., Mazzoli S. (2021). "Theory of Effective Stress in Soil and Rock and Implications for Fracturing Processes: A Review". Geosciences. 11 (3): 119. Bibcode:2021Geosc..11..119G. doi:10.3390/geosciences11030119.
  5. ^ Soil Mechanics, Lambe, T.William and Whitman, Robert V., Massachusetts Institute of Technology, John Wiley & Sons., 1969. ISBN 0-471-51192-7
  6. ^ Soil Behavior and Critical State Soil Mechanics, Wood, David Muir, Cambridge University Press, 1990. ISBN 0-521-33782-8
  7. ^ Terzaghi, K., Peck, R.B. and Mesri, G. (1996), Soil Mechanics in Engineering Practice 3rd Ed., John Wiley & Sons, Inc. ISBN 0-471-08658-4
  8. ^ Holtz, R. and Kovacs, W. (1981), An Introduction to Geotechnical Engineering, Prentice-Hall, Inc. ISBN 0-13-484394-0
  9. ^ Deep Scan Tech (2023): Deep Scan Tech uncovers hidden structures at the site of Denmark's tallest building.
  10. ^ "Geofrost Coring". GEOFROST. Retrieved 20 November 2020.
  11. ^ a b Han, Jie (2015). Principles and Practice of Ground Improvement. Wiley. ISBN 9781118421307.
  12. ^ RAJU, V. R. (2010). Ground Improvement Technologies and Case Histories. Singapore: Research Publishing Services. p. 809. ISBN 978-981-08-3124-0. Ground Improvement – Principles And Applications In Asia.
  13. ^ Pariseau, William G. (2011). Design analysis in rock mechanics. CRC Press.
  14. ^ Hegde, A.M. and Palsule P.S. (2020), Performance of Geosynthetics Reinforced Subgrade Subjected to Repeated Vehicle Loads: Experimental and Numerical Studies. Front. Built Environ. 6:15. https://www.frontiersin.org/articles/10.3389/fbuil.2020.00015/full.
  15. ^ Koerner, Robert M. (2012). Designing with Geosynthetics (6th Edition, Vol. 1 ed.). Xlibris. ISBN 9781462882892.
  16. ^ a b Dean, E.T.R. (2010). Offshore Geotechnical Engineering – Principles and Practice. Thomas Telford, Reston, VA, 520 p.
  17. ^ Randolph, M. and Gourvenec, S., 2011. Offshore geotechnical engineering. Spon Press, N.Y., 550 p.
  18. ^ Das, B.M., 2010. Principles of geotechnical engineering. Cengage Learning, Stamford, 666 p.
  19. ^ Atkinson, J., 2007. The mechanics of soils and foundations. Taylor & Francis, N.Y., 442 p.
  20. ^ Floating Offshore Wind Turbines: Responses in a Sea state – Pareto Optimal Designs and Economic Assessment, P. Sclavounos et al., October 2007.
  21. ^ Nicholson, D, Tse, C and Penny, C. (1999). The Observational Method in ground engineering – principles and applications. Report 185, CIRIA, London.
  22. ^ a b c Peck, R.B (1969). Advantages and limitations of the observational method in applied soil mechanics, Geotechnique, 19, No. 1, pp. 171-187.

References

[edit]
  • Bates and Jackson, 1980, Glossary of Geology: American Geological Institute.
  • Krynine and Judd, 1957, Principles of Engineering Geology and Geotechnics: McGraw-Hill, New York.
  • Ventura, Pierfranco, 2019, Fondazioni, Volume 1, Modellazioni statiche e sismiche, Hoepli, Milano
[edit]
  • Worldwide Geotechnical Literature Database

 

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Reviews for


Jeffery James

(5)

Very happy with my experience. They were prompt and followed through, and very helpful in fixing the crack in my foundation.

Sarah McNeily

(5)

USS was excellent. They are honest, straightforward, trustworthy, and conscientious. They thoughtfully removed the flowers and flower bulbs to dig where they needed in the yard, replanted said flowers and spread the extra dirt to fill in an area of the yard. We've had other services from different companies and our yard was really a mess after. They kept the job site meticulously clean. The crew was on time and friendly. I'd recommend them any day! Thanks to Jessie and crew.

Jim de Leon

(5)

It was a pleasure to work with Rick and his crew. From the beginning, Rick listened to my concerns and what I wished to accomplish. Out of the 6 contractors that quoted the project, Rick seemed the MOST willing to accommodate my wishes. His pricing was definitely more than fair as well. I had 10 push piers installed to stabilize and lift an addition of my house. The project commenced at the date that Rick had disclosed initially and it was completed within the same time period expected (based on Rick's original assessment). The crew was well informed, courteous, and hard working. They were not loud (even while equipment was being utilized) and were well spoken. My neighbors were very impressed on how polite they were when they entered / exited my property (saying hello or good morning each day when they crossed paths). You can tell they care about the customer concerns. They ensured that the property would be put back as clean as possible by placing MANY sheets of plywood down prior to excavating. They compacted the dirt back in the holes extremely well to avoid large stock piles of soils. All the while, the main office was calling me to discuss updates and expectations of completion. They provided waivers of lien, certificates of insurance, properly acquired permits, and JULIE locates. From a construction background, I can tell you that I did not see any flaws in the way they operated and this an extremely professional company. The pictures attached show the push piers added to the foundation (pictures 1, 2 & 3), the amount of excavation (picture 4), and the restoration after dirt was placed back in the pits and compacted (pictures 5, 6 & 7). Please notice that they also sealed two large cracks and steel plated these cracks from expanding further (which you can see under my sliding glass door). I, as well as my wife, are extremely happy that we chose United Structural Systems for our contractor. I would happily tell any of my friends and family to use this contractor should the opportunity arise!

Chris Abplanalp

(5)

USS did an amazing job on my underpinning on my house, they were also very courteous to the proximity of my property line next to my neighbor. They kept things in order with all the dirt/mud they had to excavate. They were done exactly in the timeframe they indicated, and the contract was very details oriented with drawings of what would be done. Only thing that would have been nice, is they left my concrete a little muddy with boot prints but again, all-in-all a great job

Dave Kari

(5)

What a fantastic experience! Owner Rick Thomas is a trustworthy professional. Nick and the crew are hard working, knowledgeable and experienced. I interviewed every company in the area, big and small. A homeowner never wants to hear that they have foundation issues. Out of every company, I trusted USS the most, and it paid off in the end. Highly recommend.

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