Temeltek offers Deep Soil Mixing (DSM) services as a geotechnical method . Basically Deep Soil Mixing is an effective method to improve the geotechnical feautures of the ground. Soon after we become familiar with the Deep Soil Mixing Method for Ground Improvement, Temeltek has started to provide solutions to clients by specifying proper construction procedures and equipment for different soil types which has helped assure the acquisition of the proper results in the objective grounds.
By utilizing this method, we have achieved good fabrication results at various job site. By utilizing proper procedures and equipment, adequate mixing we can create homogenous columns to depth to imrove the quality of the ground to make it geotechnically suitable for construction objectives. Temeltek has verified results from various projects all through Turkey.
The slurry is injected through the feeder attached to the arm. The process constructs individual soilcrete columns, rows of overlapping columns or 100% mass stabilization in accordance with the design specifications. The bearing capacity and global stability is deep-soil-mixing-contractor-turkeyincreaded while the settlement is decreased.The technique has been used to increase bearing capacity, decrease settlement, increase global stability with this technique. In addition it allows mitigating liquefaction potential for planned structures, tanks, embankments and levees. Situ gravity structures can be constructed with this technique along with the facilitation of tunnel construction or remediation of the impact that tunnelling may impose over the neighbouring structures. It can provide structural support and greatly reduce the lateral loads on the bulkhead walls.
Deep Soil Mixing
DSM is a soil improvement method implemented to improve soil properties without excavation or earth removal. It is an effective application for today’s geotechnical soil improvement processes and earth retention systems.
In this process, a support crane and leads are utilized which guide a series of overlapping mixing paddles and augers. As the penetration is achieved into the ground, stabilizing agents or other fluids are fed through the center of each shaft. The auger flights break the soil loose and lift it to the mixing paddles which blend the agents with the soil. Additional mixing paddles continue to mix the soil as the augers advance to greater depths. The augers are then withdrawn leaving a series of overlapping columns which form part of a wall or a treated block of soil.
Today, there are variety of uses of Soil Mixing. Soil Mixing is used for the formation of seawall, retaining walls, improving bearing capacity, cut-off walls, treating hazardous wastes in-situ and deep soil densification.
Because of the large variety of potential applications and results dependent on site-specific conditions, it is very hard to formulate one overall specification that would satisfy the requirements of all types of projects. Therefore, Temeltek offers solutions in accordance with the specific conditions of each project. This requires engineering capabilities for which we propose a highly experienced engineering team.
Tehnical Specifications
The choice in the type of the specification would be assigned by the specific application. If a specific end product with few restrictions imposed by site conditions is desired, a performance specification may be the best option. If there are various restrictions present on the equipment or method as a result of site conditions or circumstances, a custom specification which is subjective to the site conditions may be the better alternative.
A performance specification describing the final objectives for a specific project would be a preferred choice over a more subjective specification. Because of the recent developments in Deep Soil Mixing technology, a performance specification would be allowed for increased competition, innovations in equipment, and adjustments to actual site conditions. To verify adequacy of individual equipment, the specifications should be allowed for a submittal process to review expected equipment.
When we describe a Deep Soil Mixing performance specification, the guidelines contains minimum requirements for many tasks. This would include a brief description of construction procedures, basic functions of equipment, acceptable materials, and methods of field verification, applicable ASTM standards, Quality Control plans, mix designs, and methods for interpreting results.
While we describe construction procedures, at a minimum our Quality Control Plan includes horizontal and vertical alignment, mixing speed, drilling rate, flow rates, drilling sequence, and refusal criteria. Examples of achieving these criteria on other projects are as follows:
- The use of a rigid template to gauge positioning can allow the Horizontal Alignment. A stationary laser can also be used to maintain alignment on applications such as a retaining wall, where the sequence would involve a straight line.
- Through the use of instrumentation mounted on the leads of the machine, Vertical Alignment is most easily maintained. This instrumentation would read the pitch and roll in degrees from vertical and alert an operator when out of tolerance. Necessary adjustments could then be made by the operator.
- In-situ soil conditions are basic factor that determines that Mixing Speed And Drilling Rate. Significantly, we discuss these initial ranges in our Quality Control Plan.
- Flow Rate would then be determined in order to allow for sufficient additive to match drilling speed to coincide with penetration rate.
- Drilling Sequence is adjusted in a way that there wouldn’t be any discontinuities in the pattern. Drilling should advance to a specified depth or continue until refusal has been
- A decrease in penetration rate below an acceptable level will determine the Refusal Rate.
Application Standards
When specifying equipment, we allow flexibility to promote competition. If there are concerns over wall thickness or other items, we can specify the minimums, maximums or other requirements.
We submit the performance requirements through our Quality Control Plan in order to assure the quality. The quality control plan that we will provide is a description of the methods used in the project to assure proper performance. In addition, it provides a plan for verification of installation and a reporting system.
In order to verify performance, we perform a variety of field tests. Specific gravity, flow, and depth surveys can all help to control instantaneous events to maintain Quality Control. We use in-situ sampling to verify in place mixing.
These samples can be tested according to applicable ASTM standards such as:
Bu saha örnekleri aşağıda belirtilen ASTM standartlarına göre test edilmektedir:
- C 150 – Specification for Portland Cement.
- D 806-74 – Cement Content of Soil Cement Mixtures
- D 1140-54(71) – Amount of Material in Soils Finer than No. 200 Sieve.
- D 2113-83(79) – Diamond Core Drilling for Site Investigation.
- D 2216-80 – Laboratory Determination of Water (Moisture) Content of soil, Rock, and Soil-Aggregrate Mixtures.
- D 2901-82(86) – Cement Content of Freshly Mixed Soil-Cement.
- D 4380-84 – Density of Bentonitic
- D 1633 – Unconfined Compressive Strength of Soil-Cement.
- Z 1208Z (Proposed) – Test Method for Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall
Within our Quality Control plan, we dedicate a section which provides development guidelines of a mix design to meet the requirements. The development of this mix design should follow a logic flow diagram similar to the following:
- Available Knowledge of Mix Designs
- Knowledge From Similar Projects
- Mix Designs From Other Applications In Similar Soils
- Formulate Trial Mixes
- Evaluate Through Bench Scale Testing
- Use Best Option In The Field
- Does Mix Design Meet Mix Design Criteria?
- If Not, Adjust The Mix.
- Use Adjusted Mix In The Field
- Can The Mix Be Further Economized?
- If Yes, Adjust The Mix.
- Use Adjusted Mix In The Field
- Final Mix Design
The Suitable Mix Design
Especially for environmental applications, we perform a preliminary mix design test to determine an optimum additive rate. This is very useful for applications when reductions in additive rates can be a major source of economy for our clients.
We monitor the Specific gravity to verify mix design. The additive, which is most often a cement-based slurry, will reach an ideal specific gravity for the desired mix when additives are mixed in the proper proportions. Instrumentation is available to verify this quickly enough to make adjustments before pumping.
We achieve Flow Monitoring with in line flow meters. Magnetic meters tend to be more accurate with abrasive slurries. A digital readout can be set up to read instantaneous flow rate and total flow. When read in conjunction with penetration rate, the flow per foot can be monitored.
Penetration rate and total depth are best measured from the leads. A tracking device can be installed directly on the drill motor housing and track along the leads. This will read out an instantaneous penetration rate and also give a total distance traveled (depth). The alternative would be to visually measure auger Stems to determine depth.
Survey control points can be installed to verify overall position of the augers. A template is placed between these points to maintain alignment.
It is important that all parties involved in DSM project maintain flexibility and bear in mind that the most important item is an acceptable final product. No matter how many soil samples are taken, the profile of the underlying strata will most likely never be exactly known. Soil samples taken for bench scale testing may not be totally representative of subsurface conditions.
Therefore Temeltek offers methods to alter construction procedures and mix designs if necessary to produce the correct final product provided that these changes do not exceed restrictions of the project.
The clients should be looking for the mix design and/or procedure which will provide the final product the most economically.
Our past experience in DSM projects, we have seen that changes in mix designs to adapt to subsurface conditions encountered has led to more economical and expeditious DSM projects resulting in savings to all parties without compromising quality.